4.2³ = 74.088. If the 4.2 is accurate, this is actually not an estimate but an exact answer. You can of course round it to 74, then it becomes an estimate.
100 is 101 to the nearest ten
Assuming that the balls are not replaced;

= 5/42
(the numbers are decreasing in the denominator as you are presumably taking out the red balls. In the denominator, there is one less ball each time since you took out a red one).
Therefore, the probability of selected 4 red balls consecutively without replacement is 5/42.
Hope I Helped :)
The answer is letteer C. You just have to multiply 9 and pi