Questions 1 – 3 refer to the following:
Assume the amount of money seventh–grade students spend on food each day at school is exponentially distributed with an average of $2.50.Which graph best describes the distribution?
-
A
-
B
-
C
-
D
B
Find the probability that a randomly selected seventh–grade student spends less than $4 a day on food.
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A
0.7981 -
B
0.2019 -
C
0.9999 -
D
0.0001
A
85% of the seventh–grade students spend more than what amount per day?
-
A
$2.12 -
B
$0.75 -
C
$4.74 -
D
$0.41
D
Questions 4 – 5 refer to the following:
The amount of time that intermediate algebra students at Leland High School spend doing their homework per day is normally distributed with a mean 1.5 hours and standard deviation 0.75 hours.If one student is randomly chosen, what is the probability that the student does intermediate algebra homework at least 2 hours per day?
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A
0.7475 -
B
0.4259 -
C
0.2525 -
D
0.6784
C
60% of these students spend at most how many hours doing their homework?
-
A
1.69 hours -
B
1.31 hours -
C
1.5 hours -
D
0.2533 hours
A
Questions 6 – 7 refer to the following:
Llamas are excellent pack animals. It is known that the weight of supplies carried by llamas follows a normal distribution with a mean of 62.5 pounds and a standard deviation of 6 pounds.Find the probability that the weight of supplies carried by one randomly chosen llama is between 60 and 70 pounds.
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A
0.4441 -
B
0.5559 -
C
0.8944 -
D
1
B
The middle 50% of weights of supplies carried by a randomly chosen llama is between _____ and _____.
-
A
0 and 62.5 pounds -
B
58.45 and 66.55 pounds -
C
56.5 and 68.5 pounds -
D
There is not enough information given.
B
Which of the following are true for the normal distribution?
-
I
More values fall close to the mean than fall far away from the mean. -
Ii
The mean and standard deviation cannot be the same. -
Iii
A change in µ causes the graph to shift to the left or right and changes the shape of the graph. -
Iv
A change in s causes a change in the shape of the normal curve.
-
A
I, IV -
B
I, II, III, IV -
C
I, II, III -
D
III, IV
A
Questions 9 – 13 refer to the following:
The length of time junior high school students sleep per night follows an approximate uniform distribution from seven to eleven hours. Suppose we randomly select a junior high student.Find the probability that the randomly selected student sleeps less than 8 1/2 hours per night.
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A
.2143 -
B
0.7727 -
C
0.4705 -
D
0.375
D
Find the probability that the randomly selected student sleeps eight to twelve hours per night.
-
A
0 -
B
1 -
C
0.75 -
D
0.25
C
On average, how long does a junior high school student sleep per night?
-
A
.2143 -
B
0.7727 -
C
0.4705 -
D
0.375
B
On average, how long does a junior high school student sleep per night?
-
A
9.6 hours -
B
6.5 hours -
C
7.8 hours -
D
8.4 hours
D
We are interested in the probability that a randomly selected student sleeps less than eight hours, knowing that he/she sleeps less than ten. Which graph best depicts this situation?
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A
-
B
-
C
-
D
C