Question

13.The mean of a group of 20 persons was found to be 55kg. Later, it was discovered that one of them reported her weight as 45kg which was actually 54kg. Find the correct mean of their weights.
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Answer 1

Given

• The mean of a group of 20 persons was found to be 55kg. Later, it was discovered that one of them reported her weight as 45 kg which was actually 54 kg.

To find

• The correct mean

Solution

The number of persons → 20

Since , their mean found is → 55 kg

the sum of their weight → ( 55 × 20 )kg

→ 1100 kg

The actual weight of wrongly reported

girl was → 54 kg

and , the wrong weight reported → 45 kg

• ( 54 - 45 ) kg = report was 9 kg less of actual

Now, the correct sum → 1100 + 9 = 1109 kg

Here's the mean of their weight :

1109 / 20 = 55.45 kg

Therefore , the actual average was 55.45 !!