Marcy plays a game with a spinner and a 6-sided number cube. The spinner is divided into 4 equal sections numbered 1 to 4. Marcy spins the spinner and rolls the number cube. She records both numbers.
What is the probability that at least one of the numbers is a 4?

Question

Marcy plays a game with a spinner and a 6-sided number cube. The spinner is divided into 4 equal sections numbered 1 to 4. Marcy spins the spinner and rolls the number cube. She records both numbers.
What is the probability that at least one of the numbers is a 4?

greenbannanabob · Answer

I added 1/4+1/6 to 5/12, but the answer key says the answer is 9/24. I don't understand why.

greenbannanabob · Answer

to get 5/12*

welshfella · Answer

lets look at the possible outcomes

1. spinner = 4 , cube = 4   OR
2. spinner = 4 cube  not 4   OR
3. spinner not 4 , cube = 4

greenbannanabob · Answer

What about none of them getting a 4?

welshfella · Answer

1.  as these are independent events we multiply So P (4,4) = 1/4 * 1/6 = 1/24

welshfella · Answer

we are only concerned with  one 4 or above.

do you follow  the above?

greenbannanabob · Answer

I get it now. So there is a 1/24 probability that both are 4. Then there is a 3/24 probability of the cube being 4. Then there is a 5/24 probability of the spinner being a 4. Then, when all three are added together, the answer is 9/24! Is this right?

welshfella · Answer

yes 
thats correct

greenbannanabob · Answer

Thank you!

welshfella · Answer

with these compound events  where you gave  one event AND another you multiply 
when its OR - you add.

welshfella · Answer

* have not gave