Answer:
0.173 probability that she gets exactly three questions correct.
Step-by-step explanation:
For each question, there are only two possible outcomes. Either she guesses the correct answer, or she does not. The probability of guessing the correct answer for a question is independent of other questions. 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.
Seven questions:
This means that 
Each question has four choices.
Abby guesses, which means that 
Find the probability to the nearest thousandth, that Abby gets exactly three questions correct.
This is P(X = 3).


Answer:
1120 combinations of four teachers include exactly one of either Mrs. Vera or Mr. Jan.
Step-by-step explanation:
The order in which the teachers are chosen is not important, which means that the combinations formula is used to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.
In this question:
1 from a set of 2(Either Mrs. Vera or Mr. Jan).
3 from a set of 18 - 2 = 16. So

1120 combinations of four teachers include exactly one of either Mrs. Vera or Mr. Jan.
Answer:
40% profit
Step by step Explanation:
Profit percentage
=( profit/cost price) * 100
0.2 = profit/cost
10+15+20+25+30= 100
Let's assume the cost price of the items is $1 each
Cost price total= $100
Profit made when buyer of 20 toffe didn't say was
0.2=profit/cost
0.2*100 =$20
If the$ 20 paid.
Total profit = $40
So percentage profit now
40/100 * 100 = 40%
If 2 lb of bananas cost $1.16, then each pound costs $0.58.
0.58 * 5 = 2.9
So 5 lb of bananas will cost $2.90.
Hope this helps!