1.

The average height of 8 students in a class is 80 cm. If the height of 4 more students is included, then average height increased to 82 cm. Find the sum of the height of the new students.1. 240 cm2. 120 cm3. 344 cm4. 560 cm

Answer» Correct Answer - Option 3 : 344 cm

Given

Average height of 8 students = 80 cm

Average height of 12 students = 82 cm

Formula used

Average = Sum of all observation / Number of observation

Calculation

Sum of height of 8 students = 640 cm

Sum of height of 12 students = 984 cm

Sum of height of 4 students = 984 - 640

⇒ 344 cm

∴ The sum of the height of the new students is 344 cm.

Alternate method

If one or more quantities are added in a group, then the sum of new quantities added is calculated by given formula∶

Sum of new quantity = [Change in number of quantities × Original average] + [Change in average × Final number of quantities]

= [4 × 80 + 2 × 12]

⇒ 344

∴ The sum of the height of the new students is 344 cm.



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