1. The Normal Distribution
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Level 1
Level 4
Level 3
Level 2
Level 5

2. Question – Level 1
The amount of soap dispensed from a machine in a restroom is normally distributed with a mean of 0.05 ounce and a standard deviation of ounce. If the machine is used 500 times how many times would it be expected to dispense more than 0.05 ounce?
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3. Question – Level 2
A battery’s lifetime is normally distributed with a mean of 500 days and a standard deviation of 61 days. If you have 427 batteries how many would you expect to last between 439 and 561 days?
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4. Question – Level 3
A group of 625 students has a mean age of 15.8 years with a standard deviation of 0.6 years. The ages are normally distributed. How many students are at least 17 years old?
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5. Question – Level 4
The incubation period for the eggs of a House Wren is normally distributed with a mean time of 336 hours and a standard deviation of 3.5 hours. What is the probability that an egg will take more than hours to hatch?
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6. Question – Level 5
The manufacturer of a light bulb is claiming that the life span of the bulb is normally distributed, with a mean of 2000 hours and a standard deviation of 250 hours. You test 50 light bulbs. How many of the tested bulbs lasted less than 1750 hours or over 2500 hours?
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Solution – Level 1
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Solution – Level 2
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Solution – Level 3
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Solution – Level 4
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Solution – Level 5
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