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King

  • 3 years ago

: 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.

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  1. wasiqss
    • 3 years ago
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    (40x+60y)/100=48 x+y=100

  2. wasiqss
    • 3 years ago
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    solve two simoultaneous eq

  3. wasiqss
    • 3 years ago
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    boys r 60, galx 100

  4. King
    • 3 years ago
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    not possible sorry wrong answer x+y needs to be 100

  5. wasiqss
    • 3 years ago
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    sorry i mean to say galx 40

  6. wasiqss
    • 3 years ago
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    typed wrong

  7. King
    • 3 years ago
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    oh ok but how did u get first two equations....xplain

  8. King
    • 3 years ago
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    sry only first equation

  9. wasiqss
    • 3 years ago
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    listen what will be mean of marks? total marks divided by candidate

  10. King
    • 3 years ago
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    and what is x and what is y?

  11. wasiqss
    • 3 years ago
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    x is boys , y is number of galx

  12. King
    • 3 years ago
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    yeah but how 40 * x and 60 * y?

  13. wasiqss
    • 3 years ago
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    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

  14. wasiqss
    • 3 years ago
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    ok

  15. King
    • 3 years ago
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    why is 40 multiplied by x and 60 multiplied into y?

  16. wasiqss
    • 3 years ago
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    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

  17. King
    • 3 years ago
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    yeah so why do we multiply?

  18. King
    • 3 years ago
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    why do we multiply?

  19. King
    • 3 years ago
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    why do we multiply?

  20. King
    • 3 years ago
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    anwar help?

  21. AnwarA
    • 3 years ago
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    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.

  22. wasiqss
    • 3 years ago
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    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

  23. AnwarA
    • 3 years ago
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    If you solve them, you will get \(n=70 \text{ boys, and } m=30 \text{ girls}\).

  24. King
    • 3 years ago
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    no anwar u are wrong

  25. King
    • 3 years ago
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    wasiq why will we multiply if 3 students are there then mmean is x1+x2+x3/3=90

  26. AnwarA
    • 3 years ago
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    Oh sorry, I solved them for \(46\), not \(48\). Wait a sec.

  27. AnwarA
    • 3 years ago
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    60 boys and 40 girls :)

  28. King
    • 3 years ago
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    yea anwser is rite but i dont understand why we multiply...

  29. asnaseer
    • 3 years ago
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    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

  30. wasiqss
    • 3 years ago
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    king u r dumb, sorry to say bt tru

  31. asnaseer
    • 3 years ago
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    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)

  32. AnwarA
    • 3 years ago
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    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?

  33. asnaseer
    • 3 years ago
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    sorry "the total of all the items"

  34. King
    • 3 years ago
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    oh ok thnx anwar and asnaseer thnk u very much

  35. asnaseer
    • 3 years ago
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    no problem - always glad to help

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