# Math Help - basic probability

1. ## basic probability

The probability that a retired man will live 10 more yrs. is .60
The probability that a retired woman will live 10 more is .70

What is the prob. that both will be alive in 10 years?

What is the prob. that he will be alive but she won't?

What is the prob. that in 10 yrs. at least 1 will be alive?

2. Originally Posted by numnuts
The probability that a retired man will live 10 more yrs. is .60
The probability that a retired woman will live 10 more is .70

What is the prob. that both will be alive in 10 years?

What is the prob. that he will be alive but she won't?

What is the prob. that in 10 yrs. at least 1 will be alive?

Look at the addition rule for sets.

a) $P(M \cap W) =$

b) $P(M \cap W^{c}) =$

c) $P(M \cap W^{c}) + P(M^{c} \cap W) =$

3. Originally Posted by janvdl
Look at the addition rule for sets.

a) $P(M \cap W) =$

b) $P(M \cap W^{c}) =$

c) $P(M \cap W^{c}) + P(M^{c} \cap W) =$
Another hint is to assume that M and W are independent events.

4. Originally Posted by mr fantastic
Another hint is to assume that M and W are independent events.
On a side-note:
I am so out of practice with my set theory

a medicine is 80% effective - it is tested on 14 people

What is the prob. that all 14 helped?

What is the prob. that fewer than 9 of 14 will be helped?

What is the prob. that 12 or more will be helpled?

Do I use the same formulas

6. Originally Posted by numnuts
a medicine is 80% effective - it is tested on 14 people

What is the prob. that all 14 helped?

What is the prob. that fewer than 9 of 14 will be helped?

What is the prob. that 12 or more will be helpled?

Do I use the same formulas
No, you would rather use the Binomial distribution in my opinion.