Answer: A
Step-by-step explanation:
This is because 25%= 25/100, and that reduces to 1/4. Also, whenever it says something OF something, it means to multiply. In this case, 1/4 OF 1000= 1/4x1000= 250.
*Even though it seems that multiplying will just make the number bigger, when you multiply with a fraction, it actually gets smaller* For example 1/3 of 3= 1/3x3= 1
45.5%, or 4.55, for 455/1000.
91/200
Answer:
n=40
Step-by-step explanation:
25/n=5/8
25/5=5
n/5=8
n=40
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