Basic probability- expecatation and variance [on hold]

Six nickels are tossed, and the total number N of heads is observed. Then
N dimes are tossed, and the total number Z of tails among the dimes is observed.
Find the following values (either in fraction numbers or in numbers up to 4 decimal
points), and make your steps clear. (Do NOT use the Conditional Variance Formula
in any problem.)

(a) E[Z]

(b) Var(Z)

(c) P(Z = 2)

(d) E[V ar(Z|N)]

(e) Var[E(Z|N)]

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