A class contains 8 students where the sum of all their heights is 1024 cm. A kid who is 149 cm tall leaves the class. What is the difference between the old average height and the new average height?
A
2 cm
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B
5 cm
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C
1 cm
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D
3 cm
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Solution
The correct option is D
3 cm The previous sum of all the heights is 1024 cm. Therefore, the previous average is:
=SumofallobservationsTotalnumberofobservations
=10248
=128cm
Since 1 kid left, New sum = 1024 - 149 = 875 cm New number of observations = 8 - 1 =7
∴ New Average =8757
⇒125cm
∴ Difference between the averages is 128 -125 = 3 cm