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36 votes
36 votes
Could u please help me to get the answer

Could u please help me to get the answer-example-1
User Boubacar
by
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1 Answer

15 votes
15 votes

Answer:

6 6/7

Explanation:

You want the expected value of a spinner to be 3.5, when it has a 90° section valued at 4, a 60° section valued at -9, and the remaining section valued at x.

Expected value

The expected value of the spinner is the sum of the section values, each multiplied by its probability. The 360° of the spinner have a probability of 1, so the probability of a section is its degree measure divided by 360°.

expected value = 4(90/360) +(-9)(60/360) +x((360 -90 -60)/360)

3.5 = 1 -3/2 +7x/12

42 = -6 +7x . . . . . . . . . multiply by 12

48 = 7x . . . . . . add 6

x = 48/7 = 6 6/7

The value of x so the expected value of the spinner is 3.5 is 6 6/7.

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Additional comment

The unfortunate line break in the problem statement means the problem is a bit ambiguous. We assume the desired expected value is 3.5. If it is 3, then the value of x needs to be 6. (If the expected value is 3, then we don't know the meaning of the "5." on the second line.)

User Anvoz
by
2.8k points