Answer
a)$\frac{671}{1296}$
b)$1-(\frac{35}{36})^{24}$
c) A six comes up at least once when a fair dice is rolled four times.
Work Step by Step
a) The probability of rolling at least one six when a fair dice is rolled $4$ times is $P_1=1-P_1'=1-\frac{5.5.5.5}{6.6.6.6}=1-\frac{625}{1296}=\frac{671}{1296}\approx0.5177$
b) The probability that a double six comes up at least once when a pair of a
dice is rolled $24$ times is $P_2=1-P_2'=1-\frac{35}{36}\frac{35}{36}\frac{35}{36}....\frac{35}{36}=1-(\frac{35}{36})^{24}\approx 0.4914<0.5$.
c) From the calculations above, it is clear that $P_1 > P_2$, that is, the
probability of rolling at least one six when a fair dice is rolled $4$ times is
greater than the probability that a double six comes up at least once when
a pair of dice is rolled $24$ times.
