Answer:
15 seventh graders
Step-by-step explanation:
1/5 of 75 is 15
The total number of gifts = x+y.
The inequality is:

Key chains cost $1, Magnets $0.50
Total Cost = x + 0.5y
Inequality is:

Without graphing you can solve system by using substitution:

This is one solution where the maximum x value is given.
So the most keychains that can be purchased is 16. However, because magnets are cheaper, more can be purchased as long as cost remains under 20.
If you solve both inequalities for "y", you get the upper and lower bounds for how many magnets can be purchased given a quantity of keychains.

This is complete solution which gives all possible combinations.
(Graph is Attached)
Cuboid C is 4 and 4. Cuboid D is 2 and 4.
Answer:
A sample of 997 is needed.
Step-by-step explanation:
In a sample with a number n of people surveyed with a probability of a success of
, and a confidence level of
, we have the following confidence interval of proportions.
In which
z is the z-score that has a p-value of
.
The margin of error is of:

A previous study indicates that the proportion of left-handed golfers is 8%.
This means that 
98% confidence level
So
, z is the value of Z that has a p-value of
, so
.
How large a sample is needed in order to be 98% confident that the sample proportion will not differ from the true proportion by more than 2%?
This is n for which M = 0.02. So






Rounding up:
A sample of 997 is needed.
Answer:
13. 5^7
14. 7^1000
15. 16^10000
25 x 10 x 10 x 10 x 10 x 10 x 10
Step-by-step explanation: