Question

1. In a certain game, the probability of getting a red outcome is 0.03. Find the probability of getting an outcome that is not red? The answer must be in a decimal.

I put 0.97 as the answer ( 1-0.03=0.97)

2. The instructor in a Humanities class says that students have a 15% probability of making an A in her class, 20% probabilty of making a B, 25% chance of making a C, and 20% chance of making a D. The possible grades that can be assigned are A, B, C, D, and F. What is the probability that a student does not make an A?
A) 50%
B) 70%
C) 85%
D) Cannot be determined from the information given.

3. The instructor in a Humanities class says that students have a 15% probability of making an A in her class, 20% probabilty of making a B, 25% chance of making a C, and 20% chance of making a D . The possible grades that can be assigned are A, B, C, D, and F.

What is the probability that a student does not make an A or a B?

A) 35%
B) 65%
C) 3%
D) Cannot be determined from the information given.
E) 20%
F) 15%

4. The instructor in a Humanities class says that students have a 15% probability of making an A in her class, 20% probabilty of making a B, 25% chance of making a C, and 20% chance of making a D. The possible grades that can be assigned are A, B, C, D, and F.

What is the probability of a grade more than a C?

A) 60%
B) 20%
C) 35%
D) Cannot be determined from the information given.
E) 40%
F) 65%

I don't know how to answer or set up problems 2-4...

Answer 1

your #1 is correct

#2. if prob(making A) = 15%
then prob(not making A) = 100%-15% = 85%

#3. to make A or B = 15% + 20% = 35%
(since A and B are independent events, that is, you can't make both an A and a B), we can just add them up
so prob(not making A or B) = 100-35 or 65%

#4 more than C --- > either A or B which is 35%

Answer 2

Thank you!