Question

The average age of 80 boys in a class is 15. The age
of a group of 15 boys in class is 16 and the average
age of another 25 boys in class is 14. What is average
age of remaining boys in the class?
15,25 b) 14 %) 14,75 d) 14,50​

Answer 1

$\Large{\textbf{\underline{\underline{According\;to\;the\;Question}}}}$

${\boxed{\sf\:{Combined\;age\;of\;80\;Boys}}}$

= 15 × 80

= 1200

Hence we get,

= 1200 years

Now,

${\boxed{\sf\:{Combined\;age\;of\;16\;Boys}}}$

= 15 × 16

= 240

Hence we get,

= 240 years

${\boxed{\sf\:{Combined\;age\;of\;25\;Boys}}}$

= 14 × 25

= 350 years

Hence,

${\boxed{\sf\:{Combined\;Average\;of\;40\;boys}}}$

= 240 + 350

= 590

${\boxed{\sf\:{Left\;boys}}}$

= 80 - 40

= 40

${\boxed{\sf\:{Boys\;age\;Combined\;Remaining}}}$

= 1200 - 590

= 610

${\boxed{\sf\:{New\;Average}}}$

${\boxed{\sf\:{Average=\dfrac{Sum\;of\;Boys}{No\;of\;Boys}}}}$

$\tt{\rightarrow\dfrac{610}{40}}$

= 15.25 yrs

Hence we get :-

$\Large{\boxed{\sf\:{Average\;age\;of\;remaining\;boys\;in\;Class=15.25\;Years}}}$

Answer 2

Step-by-step explanation:

we know

average=sum of boys/ no.of boys

15=sum of boys/80

sum of boys=15*80=1200

so, atq

15 boys average is 16

15×16=240

and

25×14=350

total 15+25=40 boys

sum of 40 boys average 240+350=590

then remaining boys

80-40=40

remaining age sum of boys

1200-590=610

New average of remaining boys is

610/40=15.25 year's