Multiple choice

The average height of 30 boys out of a class of 50 is 160 cm. If the average height of the remaining boys is 165 cm, the average height of the whole class (in cm) is

  1. 161

  2. 162

  3. 163

  4. 164
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Total height = (30 * 160) + (20 * 165) = 4800 + 3300 = 8100. Average = 8100 / 50 = 162.

AI explanation

The total height of the first 30 boys is 30 times 160, which equals 4800 cm. The total height of the remaining 20 boys is 20 times 165, which equals 3300 cm. The overall average is the total height of all 50 boys divided by 50, calculated as (4800 + 3300) / 50, resulting in an average of 162 cm.

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