Multiple choice

The average height of 30 girls in a class of 40 is 160 cm and that of the remaining girls is 156 cm. The average height of the whole class is

  1. 157 cm

  2. 158 cm

  3. 154.5 cm

  4. 159 cm

  5. 150 cm

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Total height of 30 girls is 30 * 160 = 4800. Total height of the remaining 10 girls is 10 * 156 = 1560. Total height of 40 girls is 4800 + 1560 = 6360. Average height is 6360 / 40 = 159 cm.