A Few Probability Questions

for the top one

70% is most likley

An experiment involves selecting a numbered chip, some black and some white, from a bag of chips. The probability of selecting a black chip with an odd number is 1/4 . The probability of selecting a black chip is 2/3

.

What is the probability of selecting a chip with an odd number given that the chip is black?

(Answer as a simplified fraction please)

Let P(Black)  =  2/3

Let P(Black and Odd)  = 1/4

And  we are trying to find P( Black and Odd I Black)

So....

P( Black and Odd I  Black)  =  P( Black and Odd)  / P(Black)  = 

(1/4)  / (2/3)  = 

(1/4) * (3/2)   =

3/8

A spinner is divided into five equal sections labeled 1, 2, 3, 4, and 5. Another spinner is divided into two equal sections labeled A and B. Nigel will spin each spinner one time.

How many of the possible outcomes have a number less than 3 or an A?

We have 10  possible outcomes   =  Number Outcomes  * Letter Outcomes  =  5 * 2  = 10

So.....the ones we are interested in are

Outcomes < 3   =  2

Outcomes  = A  =  5

So.......outcomes < 3 or outcomes  = A     =  2  +  5    =   7