NAME A multiple choice test has 10 questions

Here a few of the many possible ways of answering this test: X X

Use the sequential counting principle to count all possible ways of answering the test:

Of the 59, 049 possibilities, only 1 is a perfect paper. The probability of

NAME______ Now consider the probability that you 1. Cds fvde wgryt? A) qrs B)

First, measure the probability that the first 7 answers are right and the final

The probability that the first 7 answers are right and the final 3 answers

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NAME______ A multiple choice test has 10 questions …. . 1. Cds fvde wgryt? A) qrs B) pwr C)xzy 2. Stre hyvf whjut? A) qrs B) pwr C)xzy 3. Hytre de wgryt? A) qrs B) pwr C)xzy 4. Jgrtevde wgryt? A) qrs B) pwr C)xzy 5. Chjoiide wgryt? A) qrs B) pwr C)xzy 6. Ads fvde wgryt? A) qrs B) pwr C)xzy 7. Clwiry tun gryt? A) qrs B) pwr C)xzy 8. Sqrtevde wgryt? A) qrs B) pwr C)xzy 9. Ods fvde wgryt? A) qrs B) pwr C)xzy 10. Xzzyiuhkkgryt? A) qrs B) pwr C)xzy There are 3 choices for each answer. If you guess every answer, what is the probability that you get 100% correct?

Here a few of the many possible ways of answering this test: X X X X X X X X X X X X X

Use the sequential counting principle to count all possible ways of answering the test: Step 1: answer question 1 3 Step 2: answer question 2 x 3 Step 3: Step 10: answer question 3 ………………. . . question 10 x 3 x ……………… x 3 10 = 3 = 59, 049 possible ways to fill in the answer sheet

Of the 59, 049 possibilities, only 1 is a perfect paper. The probability of guessing everything right is 1/59049 !

NAME______ Now consider the probability that you 1. Cds fvde wgryt? A) qrs B) pwr C)xzy 2. Stre hyvf whjut? A) qrs B) pwr C)xzy 3. Hytre de wgryt? A) qrs B) pwr C)xzy 4. Jgrtevde wgryt? A) qrs B) pwr C)xzy 5. Chjoiide wgryt? A) qrs B) pwr C)xzy 6. Ads fvde wgryt? A) qrs B) pwr C)xzy 7. Clwiry tun gryt? A) qrs B) pwr C)xzy 8. Sqrtevde wgryt? A) qrs B) pwr C)xzy 9. Ods fvde wgryt? A) qrs B) pwr C)xzy 10. Xzzyiuhkkgryt? A) qrs B) pwr C)xzy guess 7 right and 3 wrong.

First, measure the probability that the first 7 answers are right and the final 3 answers are wrong: # ways to answer the first 7 question 8 question 9 question 10 correctly: incorrectly: 1 x 2 x The probability that the first 7 answers are right and the final 3 answers are wrong = 8/59049 2

The probability that the first 7 answers are right and the final 3 answers are wrong = 8/59049 The number of ways of choosing a combination of 7 of the 10 questions to answer correctly = 10 C 7 = 10 x 9 x 8 x 7 x 6 x 5 x 4 7 x 6 x 5 x 4 x 3 x 2 x 1 = 120 The probability of answering 70% of the test correctly = (120) x (8/59049) = 960/59049 =. 016. . .