Answer:
(b) The probability is 0.375
(c) The probability is 0.750
Step-by-step explanation:
The probability is calculated as a division between the number of options that satisfy a condition and the total number of options.
For part (b), we have 8 cavities or options for obtain the part but we want to obtain the part from cavity 1, 2 or 3, so we have 3 options. Therefore, the probability is:

For part (c), We have 8 cavities or options for obtain the part and we want to obtain the part from any cavity except cavity 3 or 4, so we have 6 options. These options are cavity 1, cavity 2, cavity 5, cavity 6, cavity 7 and cavity 8. Then, the probability is:

Answer:
AC = 55°
Step-by-step explanation:
In this geometry, arcs AC and BD have the same measure. The sum of the parts of arc CD will total the measure of CD.
AC + AB + BD = CD
2AC +80 = 170
AC = 110/2 = 55
The measure of arc AC is 55°.
Answer:
0.0025 = 0.25% probability that both are defective
Step-by-step explanation:
For each item, there are only two possible outcomes. Either they are defective, or they are not. Items are independent of each other. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
The binomial probability is the probability of exactly x successes on n repeated trials, and X can only have two outcomes.

In which
is the number of different combinations of x objects from a set of n elements, given by the following formula.

And p is the probability of X happening.
5 percent of these are defective.
This means that 
If two items are randomly selected as they come off the production line, what is the probability that both are defective
This is P(X = 2) when n = 2. So


0.0025 = 0.25% probability that both are defective
Answer + Explanation
You look at the two denominators of the fractions and find the least common multiple of both of them.
1. the LCM of 2 and 5 is 10
2. the LCM of 3 and 5 is 15
3. the LCM of 4 and 6 is 12
4. the LCM of 6 and 9 is 18