Let the ages be:
Anu = \(A\), Bhanu = \(B\), Chanu = \(C\), Dhanu = \(D\)
Given:
1) \(A + B = 10 + B + C + D \Rightarrow A = 10 + C + D\)
2) Average age of Chanu and Dhanu = 19
\(\Rightarrow \frac{C + D}{2} = 19 \Rightarrow C + D = 38\)
3) Dhanu is 10 years elder than Chanu:
\(D = C + 10\)
Substitute \(D\) in \(C + D = 38\):
\[
C + (C + 10) = 38 \Rightarrow 2C = 28 \Rightarrow C = 14
\]
\[
D = 14 + 10 = 24
\]
Now, \(A = 10 + C + D = 10 + 14 + 24 = 48\)
Average age of Anu and Dhanu:
\[
\frac{A + D}{2} = \frac{48 + 24}{2} = \frac{72}{2} = 36
\]
Answer: The average age of Anu and Dhanu is 36 years.
We know,
So,
22% of N = 176
⇒ 22N / 100 = 176
⇒ N = (176 × 100) / 22 = 800
Total students appeared = 800
Now, 34% got first class:
First class students = 34% of 800
= (34 × 800) / 100
= 272
Online Test Series, Information About Examination,
Syllabus, Notification
and More.
Online Test Series, Information About Examination,
Syllabus, Notification
and More.
Commented Feb 06, 2021
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