average marks in english for girls :9
average marks in english for boys :8
average marks in hindi for girls :8
average marks in hindi for boys :7
overall average marks for girls and boys in English :8.8
overall average marks for girls and boys in hindi : x
then what is the value of x
Answers
Answer:
7.8
Step-by-step explanation:
Let no. of boys be "b" and no of girls be "g"
from 1st set of data, i.e score in English
9g + 8b/ g + b=8.8
solving this we get, g=4b
Now for score in hindi,
8g+7b/ g+ b= the required average
putting g= 4b from 1st equation we get
39b/5b = avg required
=39/5= 7.8
Given :
Average marks in english for girls :9
average marks in english for boys :8
average marks in hindi for girls :8
average marks in hindi for boys :7
overall average marks for girls and boys in English :8.8
overall average marks for girls and boys in hindi : x
To Find : value of x
Solution:
Boys = B
Girls = G
Average marks in english for girls :9 => Total Marks = 9G
average marks in english for boys :8 => Total Marks = 8B
average marks in hindi for girls :8 => Total Marks = 8G
average marks in hindi for boys :7 => Total Marks = 7B
overall average marks for girls and boys in English :8.8
=> 8.8 = (9G + 8B)/(G + B)
=> 8.8G + 8.8B = 9G + 8B
=> 0.8B = 0.2G
=> 4B = G
overall average marks for girls and boys in hindi = x
=> x = ( 8G + 7B)/(G + B)
=> x = (8(4B) + 7B)/(4B + B)
=> x = (32B + 7B)/5B
=> x = 39B/5B
=>x = 39/5
=> x = 7.8
Value of x is 7.8
Another way to solve :
8.8 = (9G + 8B)/(G + B)
=> 8.8 = (8G + G + 7B + B)/(G + B)
=> 8.8 = ( 8G + 7B)/(G + B) + ( G + B)/(G + B)
=> 8.8 = ( 8G + 7B)/(G + B) + 1
=> 8.8 = x + 1
=> x = 7.8
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