the mean of 10 numbers is 20.if 5 is subtracted from every number.what will be the new mean?

 Let the sum of ten numbers be 'x'

Original Mean=20

According to question

Mean=Sum of numbers/Number of numbers

=> 20=x/10

=> 200=x

Now, Modified sum can be found as follows,

Given,

From every number 5 is subtracted,

Therefore

Modified Sum=200-[10*(-5)]

=> Modified Sum=200-50=150

Now, The Modified mean can be counted as follows,

Mean=Modified Sum/Total number of observations

=> Mean=150/10

=> Mean=15

So required Answer----> The modified mean is 15.

Cheers!

Keep Smiling!