Answer:
a) 
b) 
c)  A. A student given a $1 bill is more likely to have kept the money. 
Because the probability 0.659 is atmoslt two times greater than 0.341
Step-by-step explanation:
Assuming the following table:
                                                      Purchased Gum      Kept the Money   Total
Students Given 4 Quarters              25                              14                      39
Students Given $1 Bill                       15                               29                    44
Total                                                   40                              43                     83
a. find the probability of randomly selecting a student who spent the money, given that the student was given a $1 bill.
For this case let's define the following events
B= "student was given $1 Bill"
A="The student spent the money"
For this case we want this conditional probability:

We have that 
And if we replace we got:

b. find the probability of randomly selecting a student who kept the money, given that the student was given a $1 bill.
For this case let's define the following events
B= "student was given $1 Bill"
A="The student kept the money"
For this case we want this conditional probability:

We have that 
And if we replace we got:

c. what do the preceding results suggest?
For this case the best solution is:
 A. A student given a $1 bill is more likely to have kept the money. 
Because the probability 0.659 is atmoslt two times greater than 0.341