red followed by a yellow

Mar 2010
there are 3 red spaces, 1 blue space, 3 yellow spaces, and one green space for a total of 8 spaces on a spinner. What is the probability of getting a red spin followed by a yellow spin in two spins?

I am new to probability, so I wanted to check out a couple of my homework questions.

Here is what I think:
There are n(s) = 8*8 = 64 possible spins in two total spins
n(r,y) = 3C1 * 3C1 = 9 possible reds followed by a yellow

so the probability of spinning a red then yellow in two spins is 9/64???


MHF Hall of Honor
May 2006
Lexington, MA (USA)
Hello, ihavvaquestion!

Your reasoning and your answer are both correct!

Here's another approach . . .

The probability that the first spin is Red is: \(\displaystyle \frac{3}{8}\)

The probability that the second spin is Yellow is: \(\displaystyle \frac{3}{8}\)

Therefore: .\(\displaystyle P(\text{Red, then Yellow}) \;=\;\frac{3}{8}\cdot\frac{3}{8} \;=\;\frac{9}{64}\)

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