The average height of $30$ boys was calculate to be $150 c m$ . It was detected later that one value of $165 c m$ was wrongly copied as $135 c m$ for the computation of the mean. Find the correct mean.

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Solution

Average height of $30$ boys is $150 ㎝$
Total height $= 30 \times 150$
$= 4500 ㎝$
One value is copied $135 ㎝$ which was $165 ㎝$
So, total $= 4500 + 165 - 135$
$= 4530$
So, correct mean $= \frac{4530}{30} = 151 ㎝$ $

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The average height of 30 boys was calculate to be 150 cm. It was detected later that one value of 165 cm was wrongly copied as 135 cm for the computation of the mean. Find the correct mean.

Average height of 30 boys is 150㎝Total height =30×150=4500㎝One value is copied 135㎝ which was 165㎝So, total =4500+165−135=4530So, correct mean =453030=151㎝$

The average height of $30$ boys was calculate to be $150 c m$ . It was detected later that one value of $165 c m$ was wrongly copied as $135 c m$ for the computation of the mean. Find the correct mean.

Average height of $30$ boys is $150 ㎝$
Total height $= 30 \times 150$
$= 4500 ㎝$
One value is copied $135 ㎝$ which was $165 ㎝$
So, total $= 4500 + 165 - 135$
$= 4530$
So, correct mean $= \frac{4530}{30} = 151 ㎝$ $