# Math Help - Probability question

1. ## Probability question

A biased spinner has the following scores written on it 1, 2, 3 and 4. Such that the probability that the score is 1 is 0.3 and the prob that the score is 2 is 0.6.

Ben spins the pointer once

1) what is the prob he scores 1 or 2?
Is it 0.3 + 0.6 = 0.9

2) he scores 3 or 4?
Is it 1 - 0.9 = 0.1

Rachel spins the pointer twice

3) What is the prob the score is 1 both time?
Is it 0.3 x 0.3 = 0.09

4) What is the prob the score is 2 exactly once?
NOT SURE HOW TO DO THIS ONE

2. For #4 calculate two times the probability of $(\text{a two and not a two)}$ in that order.

3. Would it be (0.6 x 0.4) + (0.6 x 0.4) = 0.24 + 0.24 = 0.48

4. Yes for all three.

For the other one, it is the probability that she gets a 2 on the first throw and another number on the second throw, OR, she scores another nubmer on the first throw and scores 2 on the second throw.

Try it out!

EDIT: Well... Natasha gave it away...