On a 30-question test, Janice answered four-fifths of the questions correctly. Which of the following is the number of questions
1 answer:
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Answer:
The expected value of the points earned on a single roll in this game is .
Step-by-step explanation:
We are given that consider a game in which players roll a number cube to determine the number of points earned. If a player rolls a prime number, that many points will be added to the player’s total. Any other roll will be deducted from the player’s total.
Assuming that the numbered cube is a dice with numbers (1, 2, 3, 4, 5, and 6).
Here, the prime numbers are = 1, 2, 3 and 5
Numbers which are not prime = 4 and 6
This means that if the dice got the number 1, 2, 3 or 5, then that many points will be added to the player’s total and if the dice got the number 4 or 6, then that many points will get deducted from the player’s total.
Here, we have to make a probability distribution to find the expected value of the points earned on a single roll in this game.
Note that the probability of getting any of the specific number on the dice is .
Numbers on the dice (X) P(X)
+1
+2
+3
-4
+5
-6
Here (+) sign represent the addition in the player's total and (-) sign represents the deduction in the player's total.
Now, the expected value of X, E(X) =
=
=
=
=
Hence, the expected value of the points earned on a single roll in this game is .