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Standard X

Mathematics

Finding Mean for Grouped Data When Class Intervals Are Not Given

Pranalee was ...

Question

Pranalee was practising for a 100 m running race. She ran 100 m distance 20 times. The time required, in seconds, for each attempt was as follows.
18, 17, 17, 16, 15, 16, 15, 14, 16, 15, 15, 17, 15, 16, 15, 17, 16, 15, 14, 15.
Find the mean of the times taken for running.

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Solution

Mean = $\frac{Sum of observations}{Number of observations}$
$Mean = \frac{18 + 17 + 17 + 16 + 15 + 16 + 15 + 14 + 16 + 15 + 15 + 17 + 15 + 16 + 15 + 17 + 16 + 15 + 14 + 15}{20}$
$\Rightarrow Mean = \frac{314}{20} = 15.7$ sec

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Pranalee was practising for a 100 m running race. She ran 100 m distance 20 times. The time required, in seconds, for each attempt was as follows. 18, 17, 17, 16, 15, 16, 15, 14, 16, 15, 15, 17, 15, 16, 15, 17, 16, 15, 14, 15. Find the mean of the times taken for running.

Mean = Sum of observationsNumber of observations Mean=18+17+17+16+15+16+15+14+16+15+15+17+15+16+15+17+16+15+14+1520 ⇒Mean=31420=15.7 sec

Pranalee was practising for a 100 m running race. She ran 100 m distance 20 times. The time required, in seconds, for each attempt was as follows.
18, 17, 17, 16, 15, 16, 15, 14, 16, 15, 15, 17, 15, 16, 15, 17, 16, 15, 14, 15.
Find the mean of the times taken for running.

Mean = $\frac{Sum of observations}{Number of observations}$
$Mean = \frac{18 + 17 + 17 + 16 + 15 + 16 + 15 + 14 + 16 + 15 + 15 + 17 + 15 + 16 + 15 + 17 + 16 + 15 + 14 + 15}{20}$
$\Rightarrow Mean = \frac{314}{20} = 15.7$ sec