The average of a class was 15 years when 5 boys whose average age was 12 years and 6 month were admitted the class average was reduced by 6 months how many were there in a class
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Let the original number of students = x
Total age in years = 15x
5 boys joined; the total age of the 5 boys = 12.5 x 5 = 62.5
Total age of all the boys in years = 15x + 62.5
Total number of students = x + 5
New average = 15 - 0.5 = 14.5
(15x + 62.5)/ (x + 5) = 14.5
From which
x = 20
∴ There were 20 students in class
Total age in years = 15x
5 boys joined; the total age of the 5 boys = 12.5 x 5 = 62.5
Total age of all the boys in years = 15x + 62.5
Total number of students = x + 5
New average = 15 - 0.5 = 14.5
(15x + 62.5)/ (x + 5) = 14.5
From which
x = 20
∴ There were 20 students in class
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Hey! ! !
Solution:
Let average age of the class was A months initially.
Total age of all students combined initially = 20 × A
Let the age of newly added boy is B months.
New average age of the class = (A – 2) months [Average decreased by 2 months]
New total age of all students combined = 20 × (A – 2) months.
∴ 20 × (A – 2) = (20 × A) – (18 × 12) + B [18 year boy replaced by B]
⇒ – 40 = B – (216)
⇒ B = 216 – 40 = 176 months = 14 years and 8 months
☆ ☆ ☆ Hop its helpful ☆ ☆ ☆
☆ Regards :- ♡♡《 Nitish kr singh 》♡♡
Solution:
Let average age of the class was A months initially.
Total age of all students combined initially = 20 × A
Let the age of newly added boy is B months.
New average age of the class = (A – 2) months [Average decreased by 2 months]
New total age of all students combined = 20 × (A – 2) months.
∴ 20 × (A – 2) = (20 × A) – (18 × 12) + B [18 year boy replaced by B]
⇒ – 40 = B – (216)
⇒ B = 216 – 40 = 176 months = 14 years and 8 months
☆ ☆ ☆ Hop its helpful ☆ ☆ ☆
☆ Regards :- ♡♡《 Nitish kr singh 》♡♡
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