I believe the problem ask for the appropriate spinner
simulation device to use among the choices. The given choices are:
1. a spinner divided into 5 congruent sectors, spun 3
times
2. a spinner divided into 5 congruent sectors, spun 4
times
3. a spinner divided into 2 congruent sectors, spun 3
times
4. a spinner divided into 2 congruent sectors, spun 4
times
The correct spinner to use among the 4 should have a
probability of winning of 80%, similar to what the owner has found out. So, we
must calculate the probability of each spinner.
1. Spun 3 times, and chance of winning is 1 in 5,
therefore P = (3) (1/5) = 0.6 = 60%
2. Spun 4 times, and chance of winning is 1 in 5,
therefore P = (4) (1/5) = 0.8 = 80%
3. Spun 3 times, and chance of winning is 1 in 2,
therefore P = (3) (1/2) = 1.5 = 150%
4. Spun 4 times, and chance of winning is 1 in 2,
therefore P = (4) (1/2) = 2 = 200%
We can see that there is only 1 choice that has 80%
probability, therefore the correct answer is:
“a spinner divided into 5 congruent sectors, spun 4 times”
