King
  • 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.
Mathematics
  • Stacey Warren - Expert brainly.com
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SOLVED
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schrodinger
  • schrodinger
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wasiqss
  • wasiqss
(40x+60y)/100=48 x+y=100
wasiqss
  • wasiqss
solve two simoultaneous eq
wasiqss
  • wasiqss
boys r 60, galx 100

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More answers

King
  • King
not possible sorry wrong answer x+y needs to be 100
wasiqss
  • wasiqss
sorry i mean to say galx 40
wasiqss
  • wasiqss
typed wrong
King
  • King
oh ok but how did u get first two equations....xplain
King
  • King
sry only first equation
wasiqss
  • wasiqss
listen what will be mean of marks? total marks divided by candidate
King
  • King
and what is x and what is y?
wasiqss
  • wasiqss
x is boys , y is number of galx
King
  • King
yeah but how 40 * x and 60 * y?
wasiqss
  • wasiqss
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
wasiqss
  • wasiqss
ok
King
  • King
why is 40 multiplied by x and 60 multiplied into y?
wasiqss
  • wasiqss
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
King
  • King
yeah so why do we multiply?
King
  • King
why do we multiply?
King
  • King
why do we multiply?
King
  • King
anwar help?
anonymous
  • anonymous
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.
wasiqss
  • wasiqss
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
anonymous
  • anonymous
If you solve them, you will get \(n=70 \text{ boys, and } m=30 \text{ girls}\).
King
  • King
no anwar u are wrong
King
  • King
wasiq why will we multiply if 3 students are there then mmean is x1+x2+x3/3=90
anonymous
  • anonymous
Oh sorry, I solved them for \(46\), not \(48\). Wait a sec.
anonymous
  • anonymous
60 boys and 40 girls :)
King
  • King
yea anwser is rite but i dont understand why we multiply...
asnaseer
  • asnaseer
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
wasiqss
  • wasiqss
king u r dumb, sorry to say bt tru
asnaseer
  • asnaseer
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)
anonymous
  • anonymous
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?
asnaseer
  • asnaseer
sorry "the total of all the items"
King
  • King
oh ok thnx anwar and asnaseer thnk u very much
asnaseer
  • asnaseer
no problem - always glad to help

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