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King
: Help..............In a school a certain number of boys and girls attend a certain examination. The mean mark of the boys was 40 and the mean mark of the girls was 60.Mean of all students is 48.Find the number of boys and girls in a class of 100.
(40x+60y)/100=48 x+y=100
solve two simoultaneous eq
not possible sorry wrong answer x+y needs to be 100
sorry i mean to say galx 40
oh ok but how did u get first two equations....xplain
listen what will be mean of marks? total marks divided by candidate
and what is x and what is y?
x is boys , y is number of galx
yeah but how 40 * x and 60 * y?
so the total marks is number of boys into their marks+number of galx nto their mean marks then divided by total number of students that s 100
why is 40 multiplied by x and 60 multiplied into y?
40 is the mean marks of boys and x is the total number of boys in class and y is total number of gals ad 60 is the mean marks of gal
yeah so why do we multiply?
OK. Let \(n\) and \(m\) be the number if boys and girls respectively, then \(40 n\) is the total points that boys scored, and \(60m\) is the total of the girls. We can then write \(\frac{40n+60m}{m+n}=48\). We also have \(m+n=100\). Solve them to find m and n.
we multiply to get the total number of marks like suppose there are 3 students in class and their mean mark is 90 so how we will get the marks obtained by class in total as in we want to add the marks of all the student
If you solve them, you will get \(n=70 \text{ boys, and } m=30 \text{ girls}\).
wasiq why will we multiply if 3 students are there then mmean is x1+x2+x3/3=90
Oh sorry, I solved them for \(46\), not \(48\). Wait a sec.
yea anwser is rite but i dont understand why we multiply...
the mean of the these 3 numbers: 12,14,16 is calculated as:\[\frac{12+14+16}{3}=\frac{42}{3}=14\]the total of those 3 numbers is: 12+14+16=42, which is the same as the mean times the number of numbers you have: 14*3=42
king u r dumb, sorry to say bt tru
so, if you are given the mean and the number of items, you can always work out the total number of items as (mean)*(number of items)
Let me explain it to you. Assume we have 5 students, and their mean is 50. We can write that as \(\large{\frac{x_1+x_2+x_3+x_4+x_5}{5}=50}\). Now if we want to find the sum of the points that all the 5 student scored, we just multiply both sides by \(5\) to get \(\large {x_1+x_2+x_3+x_4+x_5=5\times 50}\). Makes sense?
sorry "the total of all the items"
oh ok thnx anwar and asnaseer thnk u very much
no problem - always glad to help