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Given a spinner with four sections of equal size labeled

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Given a spinner with four sections of equal size labeled

by M7MBA » Sun Dec 17, 2017 8:43 am

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Given a spinner with four sections of equal size labeled A, B, C, and D, what is the probability of NOT getting an A after spinning the spinner two times?

A. 15/16
B. 9/16
C. 1/2
D. 1/4
E. 1/8

The OA is B.

How can I calculate this probability? Experts, can you give me an explanation here? Thanks.
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by EconomistGMATTutor » Sun Dec 17, 2017 9:54 am
Given a spinner with four sections of equal size labeled A, B, C, and D, what is the probability of NOT getting an A after spinning the spinner two times?

A. 15/16
B. 9/16
C. 1/2
D. 1/4
E. 1/8

The OA is B.

How can I calculate this probability? Experts, can you give me an explanation here? Thanks.
Hi M7MBA,
Let's take a look at your question.

Probability of Not Getting an A after spinning the spinner two times can be calculated as:
$$P\left(\text{Not getting an A}\right)\times P\left(\text{Not getting an A}\right)$$
$$=\frac{3}{4}\times\frac{3}{4}=\frac{9}{16}$$

Therefore, option B is correct.

Hope it helps.
I am available if you'd like any follow up.
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by Brent@GMATPrepNow » Sun Dec 17, 2017 2:01 pm
M7MBA wrote:Given a spinner with four sections of equal size labeled A, B, C, and D, what is the probability of NOT getting an A after spinning the spinner two times?

A. 15/16
B. 9/16
C. 1/2
D. 1/4
E. 1/8
Since the 4 sections each have EQUAL sizes, P(getting A on a single spin) = 1/4
So, P(NOT getting A on a single spin) = 1 - 1/4 = 3/4

What is the probability of NOT getting an A after spinning the spinner two times?
P(neither spin lands on A) = P(no A on 1st spin AND no A on 2nd spin)
= P(no A on 1st spin) x P(no A on 2nd spin)
= 3/4 x 3/4
= 9/16
= B

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by Scott@TargetTestPrep » Wed Sep 18, 2019 8:48 am
M7MBA wrote:Given a spinner with four sections of equal size labeled A, B, C, and D, what is the probability of NOT getting an A after spinning the spinner two times?

A. 15/16
B. 9/16
C. 1/2
D. 1/4
E. 1/8

The OA is B.

How can I calculate this probability? Experts, can you give me an explanation here? Thanks.
The probability of not getting an A each spin is ¾. Therefore, the probability of not getting an A twice in two spins is ¾ x ¾ = 9/16.

Answer: B

Scott Woodbury-Stewart
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