You spin a spinner and the probability that the spinner will land on red is 18%. Suppose you spin the spinner 4 times. What is the probability that the spinner will land on red at least 2 times?

Question

You spin a spinner and the probability that the spinner will land on red is 18%.  Suppose you spin the spinner 4 times.  What is the probability that the spinner will land on red at least 2 times?

anonymous · Answer

binomial probability for this one

anonymous · Answer

at least 2 means 2 or 3 or 4
you can compute each, or else compute the probability you get no reds and subtract from 1
which would you prefer?

anonymous · Answer

doesn't matter to me

anonymous · Answer

am I using binomial probability

anonymous · Answer

the probability you get red is .18 so the probability you get no red is .82 
the probability you get no red 4 times in a row is therefore $(.82)^4$

anonymous · Answer

then the probability you get exactly one red is 
$$4\times (.82)^3\times (.12)$$

anonymous · Answer

those are the "binomial" probabilities

anonymous · Answer

you can compute those two numbers, add them, and then subtract the result from one

anonymous · Answer

The answer I get is 74% but that is not an option for me.  My choices are 10.1%,  11.9%,  24.3% or 63.8%.

anonymous · Answer

Is the 74% that I get not reds so is my answer 24.3%