A consumer organization estimates that over a period of one year 16 percent of cars will need to be repairedonce, 7 percent will need repairstwice, and 2 percent will require three or more repairs. What is the probability that a car chosen at random will need no repairs?

a. 0.25

b. 0.75

c. 0.77

d. 0.23

An orthodontist has three financingpackages, and each has a different service charge. He estimates that about 30% of the patients use the first plan which has a service charge of $100; 15 % use use the second plan which has a service charge of $150, and remaining use the third plan which has a service charge of $300. The expected service charge for a random patient, in dollars, is:

a. 218

b. 73

c. 436

d. 415

In a class on probability, a statistics professor flips two balanced coins. Both fall to the floor and roll under his desk. A student in the first row informs the professor that he can see only one coin and it shows "tails". What is the probability that the other coin also shows "tails"?

a. 1/3

b. 1/2

c. 2/3

d. 1/4