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The traffic police recorded the speed (in kmlhr) of 10 motorists as 47, 53, 49, 60, 39, 42, 55,57, 52, 48. Later on an error in recording instrument was found. Find the correct overagespeed of the motorists if the instrument recorded 5 km/hr less in each case.

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#### Solution

The speed of 10 motorists are 47, 53, 49, 60, 39, 42, 55, 57, 52, 48

Later on it was discovered that the instrument recorded 5km/hr less than in each case

Corrected values are 52, 58, 54, 65, 44, 47, 60, 62, 57, 53

∴ Correct mean = `(52 + 58 + 54 + 65 + 44 + 47 + 60 + 62 + 57 + 53)/ 10`

= `552 / 10`

= 55 . 2 km/ hr

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