Probability — Test Answers

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Based on this dotplot and the sample of last month’s on-time completions, which conclusion can be drawn?

A
It is most likely that the contractor will complete about 9 out of 10 jobs.
B
The contractor’s true, on-time completion rate is only 50 percent .
C
If we used a larger sample size of 40 jobs, the simulated dotplot would be different; therefore, we cannot draw a conclusion.
D
The dotplot does not provide convincing evidence that her true, on-time completion rate is less than 90 percent because 7 or fewer on-time completions happened 19 percent of the time in the simulation.
3

Which of the following is the correct value and interpretation of cap p times open paren cap b divides cap f close paren ?

A
cap p times open paren cap b divides cap f close paren is equal to 0 point 4 5 ; given that the student has fair dancing skills, there is a 0 point 4 5 probability that they prefer to write with block letters.
B
cap p times open paren cap b divides cap f close paren is equal to 0 point 3 7 ; given that the student has fair dancing skills, there is a 0 point 3 7 probability that they prefer to write with block letters.
C
cap p times open paren cap b divides cap f close paren is equal to 0 point 3 7 ; given that the student prefers to write with block letters, there is a 0 point 3 7 probability that they have fair dancing skills.
D
cap p times open paren cap b divides cap f close paren is equal to 0 point 4 5 ; given that the student prefers to write with block letters, there is a 0 point 4 5 probability that they have fair dancing skills.
4

Based on the dotplot of the simulation results and the pool player’s last 20 games, which conclusion can be drawn?

A
The player’s true probability of sinking at least one ball on her break is 27 percent .
B
There is about a 27 percent chance of her sinking at least one ball on her break 14 or fewer times in 20 games. This result is not unusual and there is no convincing evidence that her average is less than 80 percent .
C
It is most likely that she would sink at least one ball during her break exactly 16 times.
D
Another 100 simulated trials would show a much different outcome; therefore, we cannot draw any conclusions.
8

Which of the following is the correct value and interpretation of cap p times open paren cap f divides cap b close paren ?

A
cap p times open paren cap f divides cap b close paren is equal to 0 point 5 8 ; given that the student’s strongest stroke is freestyle, there is a 0 point 5 7 probability that they prefer brand B.
B
cap p times open paren cap f divides cap b close paren is equal to 0 point 5 1 ; given that the student’s strongest stroke is freestyle, there is a 0 point 5 1 probability that they prefer brand B.
C
cap p times open paren cap f divides cap b close paren is equal to 0 point 5 1 ; given that the student prefers brand B, there is a 0 point 5 1 probability that their strongest stroke is freestyle.
D
cap p times open paren cap f divides cap b close paren is equal to 0 point 5 8 ; given that the student prefers brand B, there is a 0 point 5 7 probability that their strongest stroke is freestyle.
9

Suppose a high school student is selected at random. Let event cap A is equal to junior and event cap b is equal to fiction. Are events cap A and cap b independent?

A
Yes, cap p times cap A is equal to cap p times open paren cap A divides cap b close paren .
B
No, cap p times cap A is not equal to cap p times open paren cap A divides cap b close paren .
C
No, cap p times cap A is not equal to cap p times open paren cap b divides cap A close paren .
D
Yes, cap p times cap A is equal to cap p times open paren cap b divides cap A close paren .
12

Does this provide convincing evidence that seniors at Garfield High School study more than the report stated?

A
No, there were outcomes as low as 12.
B
No, there is an outlier at 20.
C
Yes, more than half of the simulated results are over 15.
D
Yes, only one trial had a result of 19 or larger.
16

A security alarm requires a four-digit code. The code can use the digits 0 - 9 and the digits cannot be repeated. Which expression can be used to determine the probability of the alarm code beginning with a number greater than 7 ?

A
the fraction with numerator open paren sub 10 cap c sub 1 close paren times open paren sub 9 cap c sub 3 close paren and denominator sub 10 cap c sub 4
B
the fraction with numerator open paren sub 10 cap p sub 1 close paren times open paren sub 9 cap p sub 3 close paren and denominator sub 10 cap p sub 4
C
the fraction with numerator open paren sub 2 cap c sub 1 close paren times open paren sub 9 cap c sub 3 close paren and denominator sub 10 cap c sub 4
D
the fraction with numerator open paren sub 2 cap p sub 1 close paren times open paren sub 9 cap p sub 3 close paren and denominator sub 10 cap p sub 4
17

A cereal company hopes to increase its sales by putting prizes in randomly selected boxes of its lowest-selling children’s cereal. The company claims that the probability of getting a prize is 0 point 7 5 Which is the correct interpretation of this probability?

A
In many, many boxes of cereal of this type, we can expect about 75 percent of the boxes to contain a prize.
B
There is a guarantee of getting 3 prizes when buying 4 boxes of this type of cereal.
C
The claim of this company is correct if exactly 75 out of 100 boxes of this type of cereal contain a prize.
D
This company expects to increase cereal sales by 75 percent .

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