When 10 is subtracted from each of the given observations, the mean is reduced to 60%. If 5 is added to all the given observations, the mean will be:

Solution
Given:
When 10 is subtracted from each of the given observations, the mean is reduced to 60%.
Concept used:
Total = Mean × Number of entities
Calculation:
When 10 is subtracted from each of all observations, apparently the mean will reduce by 10.
Let the initial mean be M.
According to the question,
M – 10 = M × 60%
⇒ M – 10 = 0.6M
⇒ 0.4M = 10
⇒ M = 25
Again if 5 is added to all observations, apparently the mean will increase by 5.
Now, the mean becomes = 25 + 5 = 30
∴ If 5 is added to all the given observations, the mean will be 30.