Test Papers – ICSE – Class – X
MBA Entrance, Quantitative Aptitude, Alligation and Successive Percentage, Module 2
Hi, in this session will be learning about successive percentages now what really is a successive percentage it is percentage on percentage didn’t understands ok let’s do that with this example A scores 10% more than B, while B scores 20% more than C . By what percentage did is A score more than C right so if we go with the method of base hundred right since he has score least number of marks let’s assume the mark scored by C as 100 we know that B has scored 20% more than him so he would have scored 120 right it’s obvious however A has scored 10% more than B what that means is if B has scored 120, 10% of 120 will be 12 so A has got 12 more than 120 which is 132 so now I compare A’s marks with C’s marks its clear that A has scored 32% more than C the correct answer is 32% right this is what is successive percent we have already increase the value by certain percent and increase the change value by some other percent and that is called successive percent, percent on percent now it could be increased or decreases will see that later but a better way of understanding by this diagram
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MBA Entrance, Quantitative Aptitude, Alligation and Successive Percentage, Module 1
Hi, in this session will be learning about alligation now what really is alligation well alligation is a method of finding the ratio in which two or more ingredients should be mixed in order to make a mixture of a desired proportion so we’re mixing two or more quantities alligation is a process mixing it in a desired ratio in order to obtain a particular proportion Let us see with this example in what ratio should you mix two varieties of tea powder one costing 10 per kg and other costing 25 per kg, so as to get a mixture at an average price of 15 per kg now if you realize the difference between the weighted average and alligations is that in weighted average you are given the weights or the ratio in which two ingredient should be added and you are supposed to find the average where is in this case they have given you the average price and you are supposed to find the ratio in which it should be mixed so let’s go back to the lever that we learnt in weighted average so we have to lever and at the end point with the two values 10 and 25 in this case the only difference is we know the average so the balancing point of the lever is known that is 15 per kg so what is the difference from this average from each of the two values as you can see it is 5 from other end and 10 from this end which means the ratio of the differences is 1:2 to 5:10 which is 1:2 and as you know the ratio of the mixing should be reversed right which means the ratio in which these two quantities should be mixed must be 2:1 right and that’s your answer which means alligation and weighted average are two sides of the same coin it’s just that what we need to find and what is given is reverse so what will do is will learn alligation using a slightly different method which is just the modification of this method right for that
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MBA Entrance,Quantitative Aptitude, Introduction To Percentage, Concept Of Percentage Change
Hello, now let’s look at the concept of percentage A is 25% taller than B this is what we have done in the previous video correct but now the statement is 25% taller than B by what percentage is B shorter than A so let’s see how to approach this question so what is my base here B and 25% is 1 by 4 so this is what we have done that if B is 4, A would be 5 correct this is what we have done earlier now the next question what percentage is B shorter than A so what is my base here A so the comparison in respect to A what is A now 5 and B is 4 which will be 1 less than A which means 4 is 1 less than 5 which means B is how much percentage shorter than A, 1 by what is base A so 1 upon 5 which means B is 20% shorter than A I hope it’s clear to everyone let’s move ahead and see the next example X scores 4.75 % less than Y, by what percentage has Y scored more than X what is a comparison base in the first statement Y and what is 4.75 % 1/21 which means if we assume that Y is 21 then X would be 1 less than 21 which means X would be 20 now in the next statement base become X correct if X is 20 and Y was 21 as per the previous diagram the left hand side diagram which means Y that is 21 is 1 more than 20 so it is 1 upon 20 which is nothing but is 5% so Y has scored 5% more than X lets move ahead if A is 10% more than B, then B is what percent less than A
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MBA Entrance,Quantitative Aptitude, Introduction To Percentage, Percentage Increase And Decrease
Hello today we look at percentage increase and decrease what do you mean by this statements A is 25% taller, sales of the company decreased by 15%, X scored 30%, Y scored 20% does these statement makes any meaning no why because the comparison is missing A is 25% taller than whom, sales of the company decrease by 15% with respect to what so now if I write down A is 25% taller than B compared to last year, sales of the company decreased by 15% over last year than the expectation does it make sense yes similarly X scored 30% out of 50 in only section 1 and Y scored 20% out of 200 of the total they are meaningful statements so the base the comparison is very very important now if we look at A is 25% taller than B what is my base here B there are various approach to simply solve this question lets go ahead with first method that is method of base 100 so if you assume that height of B is 100 then A will be 25 more than 100 which means A is 125 clear everyone if we go ahead with the second method which is multiplying factor if I assume the height of B as B then height of A would be 1.25 times of B clear the second method let’s look at some other example A is 5.88% taller than B what is my base here B so what is my first method base 100 if we assume height of B is 100 then height of A would be 5.88 more than 100 that is nothing but 105.88 is that scary because 105.88 working with decimal correct and if you look at the second method that is multiplying factor over there we assume the height B as B then the height of A will becomes 1.0588 times of B my god you can just imagine the level of calculation correct so to simplify this if the percentages are keyds will use the next two methods
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MBA Entrance, Quantitative Aptitude, Averagers, Module 3
Hi, in this session we are going to look at other methods of computing means you’re already aware of arithmetic mean which is simple average and also weighted average Now there are other methods of computing mean apart from these two let us look at what are they the first one is nothing but geometric mean now how do we compute Geometric mean of in values what we need to do is we need to take the product of these n values and take the end root and that is how we compute the geometric mean simply multiply the n values and take the nth root right let’s take it look at it from examples let’s say we have to compute the geometric mean of 10, 20 and 30 as per the rule what are we suppose to do well multiply these 3 values 10 into 20 into 30 and take the cube root because there are three values will take the cube root now what is 10 into 20 into 30 is 6000 so the final answer would be 6000 cube root of that now you already know that I can split 6000 as 6 into 1000 and what is cube root of 1000 well cube root of thousand is 10 right now you can always split it this way and 10 goes out and we get 10 into cube root of 6 and that is the geometric mean of 10, 20 and 30 I hope you understood geometric mean let us now look at the next mean and that is nothing but harmonic mean have you heard of this first ok how do you compute harmonic mean of n values simple divide n by sum of the reciprocals of the n values as in n/1/n1+1/n2+1/n3 and all the way till n n so your adding the reciprocals of these n values that’s your denominator and number values are in numericals there n values so there will in the power of numerical that’s harmonic mean right for example what is the harmonic mean of 4, 8 and 9
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MBA Entrance Quantitative Aptitude, Averages, Module 1
Hi this seesion is about Arithmetic mean or simple average what really is arithmetic mean to understand this we need to look at the monthly rainfall figures of Colombo in the year 2012 this is the graph which depicts the monthly rainfall figures in 2012 right you need to find the average monthly rainfall in this particular year so how do you go about it Arithmetic mean or simple average is nothing but sum of all values upon the total number of values so what exactly needs to be done well as the formula suggested you need to add up all these 12 values right what’s the sum of all these 12 values if you add them the sum is 3000 and how many values have we added in all monthly right so in a year there are 12 months so we have added 12 values so the Arithmetic mean or simple average would be nothing but 3000 divided by 12 which is 250 in short in the year 2012 Colombo had an average monthly rainfall of 250 Milli-meters but you would have realize that in doing so it took a lot of time because we had to add so many big values isn’t there any other way around well that’s not the case we have an interesting method of finding Arithmetic mean which circumvents this difficult calculations what is that well that’s called the method of assumed mean what do you do in this method we assume the mean to be one of the values which is somewhere in between the highest and the lowest for example in this case the highest is 600 and the lowest is somewhere in the range of hundred for example this way so what we do is we assume the rainfall the average rainfall to be 200 well I am not suggesting that the actual average is 200 we are just assuming the value to be 200 now what we do is we find all the positive deviations which means the deviations of all the values which are more than 200 from 200 for example these are the values which are more than 200 and the deviations as you can see are 170, 350, 400, 120 and 20 deviations are nothing but the difference between the actual values and the assumed mean right likewise will go on to find out the negative deviation which means the deviations of those values which are less than the assumed mean these right so for example 130 is 70 less 150 is 50 less than you assume mean ow what is the advantage of doing this
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