The average height of some studentsin a groupis 156 cm If 5 students of average height 160 cm join t...........

Quantitative Aptitude (CGL) Average

The average height of some studentsin a groupis 156 cm.If 5 students of average height 160 cm join the group. then the

averageheight ofall the students in the group increases by 0.8 cm. Whatis the numberof students in the group, initially?

This questions was previously asked in

SSC CGL 16th August 2021 Shift-3

- Let the initial number of students be \( n \) with an average height of 156 cm.

- Total height of initial group = \( 156n \).

- 5 new students join, each with an average height of 160 cm.

- Total height added = \( 5 \times 160 = 800 \).

- New average height = initial average + 0.8 cm = 156 + 0.8 = 156.8 cm.

- New total number of students = \( n + 5 \).

- New total height = \( 156n + 800 \).

- New average height equation: \((156n + 800) / (n + 5) = 156.8\).

- Solving gives: \( 156n + 800 = 156.8n + 784 \).

- Simplifying: \( 16 = 0.8n \), so \( n = 20 \).

- Option 1: 10 - Too low.

- Option 2: 15 - Still low.

- Option 3: 20 - Correct calculation.

- Option 4: 25 - Too high.

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