# Question: The reading speed of second grade students is approximately normal

The reading speed of second grade students is approximately normal, with a mean of 90 words per minute (wpm) and a standard deviation of 10 wpm.

(a) What is the probability a randomly selected student will read more than 95 words per minute?

(b) What is the probability that a random sample of 12 second grade students results in a mean reading rate of more than 95 words per minute?

(c) What is the probability that a random sample of 24 second grade students results in a mean reading rate of more than 95 words per minute?

(d) What effect does increasing the sample size have on the probability? Provide an explanation for this result.

(e) A teacher instituted a new reading program at school. After 10 weeks in the program, it was found that the mean reading speed of a random sample of 20 second grade students

was 92.8 wpm. What might you conclude based on this result?

(f ) There is a 5% chance that the mean reading speed of a random sample of 20 second grade students will exceed what value?

(a) What is the probability a randomly selected student will read more than 95 words per minute?

(b) What is the probability that a random sample of 12 second grade students results in a mean reading rate of more than 95 words per minute?

(c) What is the probability that a random sample of 24 second grade students results in a mean reading rate of more than 95 words per minute?

(d) What effect does increasing the sample size have on the probability? Provide an explanation for this result.

(e) A teacher instituted a new reading program at school. After 10 weeks in the program, it was found that the mean reading speed of a random sample of 20 second grade students

was 92.8 wpm. What might you conclude based on this result?

(f ) There is a 5% chance that the mean reading speed of a random sample of 20 second grade students will exceed what value?

## Answer to relevant Questions

The most famous geyser in the world, Old Faithful in Yellowstone National Park, has a mean time between eruptions of 85 minutes. If the interval of time between eruptions is normally distributed with standard deviation 21.25 ...The Food and Drug Administration sets Food Defect Action Levels (FDALs) for some of the various foreign substances that inevitably end up in the food we eat and liquids we drink. For example, the FDAL for insect ﬁlth in ...Technically, we assume that we are obtaining simple random samples from inﬁnite populations when obtaining sampling distributions. If the size of the population is ﬁnite, we technically need a ﬁnite population ...A simple random sample of size n = 200 is obtained from a population whose size is N = 25,000 and whose population proportion with a speciﬁed characteristic is p = 0.65. A shipment of 50,000 transistors arrives at a manufacturing plant. The quality control engineer at the plant obtains a random sample of 500 resistors and will reject the entire shipment if 10 or more of the resistors are ...Post your question