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# Probability of Random Selection

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1. Assume that a class length between 50.0 min and 52.0 min is randomly selected, and find the probability that the given time is seletced.

Between 50.5 min and 51.8 min

2. Assume that voltages in a circuit vary between 6 volts and 12 volts, and voltages are spread evenly over the range of possibilities, so that there is a uniform distribution. Find the probability of the given range of voltage levels.

Between 6.5 volts and 8 volts.

3. Assume that the readings on scientific thermometers are normally distributed with a mean of 0 degrees C and a standard deviation of 1.00 degrees C. A thermometer is randomly selected and tested. In each case draw a sketch, and find the probability of each reading in degrees Celcius.

Greater than -1.96

Between -3.88 and 1.07

4. Find the indicated area under the curve of the standard normal distribution, then convert it to a percentage and fill in the blank.

About___% of the area is between z = -3.5 and z = 3.5 (or within 3.5 standard deviation of the mean)

5. Assume that the readings on the thermometers are normally distributed with a mean of 0 degrees C and a standard deviation of 1.00 C. Find the indicated probability, where z is the reading in degrees.

P(1.96 < z <2.33)

https://brainmass.com/statistics/quantative-analysis-of-data/probability-random-selection-293558

#### Solution Preview

Hi,

Please find the solutions/explanations attached herewith.

In each case round to desired decimal places.

1. Assume that a class length between 50.0 min and 52.0 min is randomly selected, and find the probability that the given time is seletced.

Between 50.5 min and 51.8 min

P(50.5 < x< 51.8) = (51.8-50.5)/(52-50) = 0.65