Answer:
80%; 30%
Step-by-step explanation:
There is 5 blue marbles, 2 black marbles, and 3 red marbles. In other words, there is a total of 10 marbles.
There are only 2 black marbles and 8 marbles that are not black. Therefore, the probability of <em>not</em> drawing a black marble is 8/10 or 4/5 or 80%.
There are only 3 red marbles out of the 10 total marbles. Therefore, the probability of drawing a red marble is 3/10 or 30%.
We have the mean, μ = 20 and the standard deviation, σ = 4
X ≈ N(20, 4²)
We want P(X<15)
Standardising gives
P(X<15) = P(Z<

)
P(X<15) = P(Z< -1.25) ⇒ When the value of the z-score is negative, we will read the value of z<1.25 on the z-table then subtract the answer from 1
P(X<15) = 1 - P(Z<1.25)
P(X<15) = 1 - 0.8944
P(X<15) = 0.1056
Hence, the probability that pizza takes less than 15 minutes to be delivered is 0.1056 = 10.56%