Question 1028488
A.) The number of tails seen in 50 tosses of a quarter.
If the quarter is unbiased, then the mean should be 50*0.5 = 25.  Variance should be 50*0.5*0.5 = 12.5, and hence standard deviation is {{{sqrt(12.5) = 3.54}}} approximately.

B.) The number of aces seen in 100 draws from a well-shuffled bridge deck(without replacement).
Assuming an infinite population (so that the non-replacement is immaterial), the mean is {{{100*(1/13) = 100/13}}}, while the variance is {{{100*(1/13)*(12/13) = 1200/169}}}, hence the standard deviation is {{{sqrt(1200/169) = (20sqrt(3))/13 = 2.66}}} approximately.

C.) The number of cars found to have unsafe tires among the 400 cars stopped for inspection. Assume 6% of all cars have one or more unsafe tires.
Mean would be {{{400*0.06 = 24}}}, and standard deviation is {{{sqrt(400*0.06*0.94) = sqrt(22.56) = 4.75}}} approximately.

D.)  I leave this up to you.