1.

Out of 10 boys, 4 boys of 1 m 40 cm height, 3 are of 1 m 62 cm height and rest are of 1 m 73 cm height. What is the average height of all boys. 1. 156 cm2. 158 cm3. 156.5 cm 4. 155.5 cm

Answer» Correct Answer - Option 3 : 156.5 cm 

Given:

Total numbers of boys = 10

Height of 4 boys = 1 m 40 cm = 140 cm

Height of 3 boys = 1 m 62 cm = 162 cm

Height of rest boys = 1 m 73 cm = 173 cm

Formula used :

Average = (sum of total observations)/(total numbers of observations) 

Calculation:

Total numbers of boys = 10

Numbers of rest boys = 10 – 4 – 3 = 3 boys

Sum of  height first 4 boys = 4 × 140 cm

⇒ Sum of  height first 4 boys = 560 cm

Sum of  height 3 boys = 3 × 162 cm

⇒ Sum of  height 3 boys = 486 cm

Sum of  height rest 3 boys = 3 × 173 cm

⇒ Sum of  height rest 3 boys = 519 cm

Total height of 10 boys = (560 + 486 + 519) cm

⇒ Total height of 10 boys = 1565 cm

Average = (sum of total observations)/(total numbers of observations) 

⇒ Average of height of 10 boys = (1565)/10

⇒ Average of height of 10 boys = 156.5

∴ Average of height of all boys is 156.5.



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