There were 24 students in a class. One of them, who was 18 y

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RRB ASM Exam (Ajmer) 2007 click here to view all questions

There were 24 students in a class. One of them, who was 18 yr old, left the class and his place was filled up by a newcomer. If the average of the class thereby,was lowered by one month. The age of the newcomer is-

A14 yr

B15 yr

C16 hr

D17 yr

Nithin K ? Nov 20 '2016 at 21:58

Answer is : 16 hr

Explanation:

There were 24 students in a class.
No. of students in class = 24 ....................(i)

If the average of the class thereby,was lowered by one month
Average age decreased by = 1 month = \(\frac{1}{12} \)years..................(ii)

Let new comer age was x.
One of them, who was 18 yr old, left the class and his place was filled up by a newcomer.

= 18 - x ...............................(iii)

No. of students in class* aged decreased = difference of replacement
From equation (i),(ii) and (iii)
\(24 * \frac{1}{12} = 18 - x\)
\(2 = 18 - x\)
\(x = 16 years.\)
Age of new comer age was 16 years.

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Answer is : 16 hr Explanation: There were 24 students in a class. No. of students in class = 24 ....................(i) If the average of the class thereby,was lowered by one month Average age decreased by = 1 month = \(\frac{1}{12} \)years..................(ii) Let new comer age was x. One of them, who was 18 yr old, left the class and his place was filled up by a newcomer. = 18 - x ...............................(iii) No. of students in class* aged decreased = difference of replacement From equation (i),(ii) and (iii) \(24 * \frac{1}{12} = 18 - x\) \(2 = 18 - x\) \(x = 16 years.\) Age of new comer age was 16 years. Nithin K ? answered Nov 20 '2016 at 21:58 All Comments

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