Question

8 number mean 21 , then all number multiple by 8 the answers is

Answer 1

Mean of numbers will not change if multply all the numbers by same quantity.

So, even after Multiplying by 8, mean will be 21

Answer 2

The mean of the given no. will not change if multiply all the numbers by the same quantity.
Even though after multipling 8 the mean remains the same i.e 21.
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Hope it helps ☺