Question

a) Assume that the readings at freezing on a bundle of thermometers are normally distributed with a mean of 0°C and a standard deviation of 1.00°C. A single thermometer is randomly selected and tested. Find P84, the 84-percentile. This is the temperature reading separating the bottom 84% from the top 16%. P84 = *blank* °C

b) Assume that the readings at freezing on a bundle of thermometers are normally distributed with a mean of 0°C and a standard deviation of 1.00°C. A single thermometer is randomly selected and tested.

If 2.8% of the thermometers are rejected because they have readings that are too high and another 2.8% are rejected because they have readings that are too low, find the two readings that are cutoff values separating the rejected thermometers from the others.

interval of acceptable thermometer readings =

c) Suppose that a brand of lightbulb lasts on average 2404 hours with a standard deviation of 105 hours. Assume the life of the lightbulb is normally distributed. Calculate the probability that a particular bulb will last from 2359 to 2539 hours?

P(2359 < X < 2539) =

Enter your answer as a number accurate to 4 decimal places.

*Note: all z-scores must be rounded to the nearest hundredth.

Answer 1

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