E[aX+b] = aE[X] + b

Var[aX+b] = (a^2) Var[X]

SD[aX] = (Var[aX])^(1/2) = a * SD[X]

Multiplying SD by a changes SD and mean both by a.

Mean change from 6.6 to 12.05 as multiplied by 4.2/2.3

SD measures spread so, adding constant to all values doesn’t change SD.

PS: More Info : https://math.stackexchange.com/questions/2793239/does-standard-deviation-change-if-multiplied-by-a-constant-or-if-a-constant-is