Chapter 9, Problem 17E

(a)

To determine

To explain does this graph indicate that students are making satisfactory progress in reading or not.

Answer to Problem 17E

This graph indicates that students are making satisfactory progress in reading.

Explanation of Solution

To measure progress in reading ability, the students at an elementary school take a reading comprehension test every year. Scores are measured in grade level units. The school principal prepares a report to parents that include a graph showing the mean recording score of each grade. The scatterplot of average reading level versus grade is given in the question. The graph indicates that on average student progress at about one reading level per year. This graph shows average to each grade. The linear trend has been enhanced by using averages.

(b)

To determine

To explain what do you estimate correlation between grade and average reading level to be.

Answer to Problem 17E

Correlation between grade and average reading level should be very close to one.

Explanation of Solution

To measure progress in reading ability, the students at an elementary school take a reading comprehension test every year. Scores are measured in grade level units. The school principal prepares a report to parents that include a graph showing the mean recording score of each grade. The scatterplot of average reading level versus grade is given in the question. By looking at the graph in the question, we can say that the points are moving in the upward direction. So, by this we can conclude that we can estimate correlation between grade and average reading level to be very close to one.

(c)

To determine

To find out would you expect correlation to be the same, higher or lower.

Answer to Problem 17E

The correlation would be lower.

Explanation of Solution

To measure progress in reading ability, the students at an elementary school take a reading comprehension test every year. Scores are measured in grade level units. The school principal prepares a report to parents that include a graph showing the mean recording score of each grade. The scatterplot of average reading level versus grade is given in the question.As by looking at the scatterplot we can say that the individual data would show much more scatter and that is why the correlation would be lower.

(d)

To determine

To explain what value of the slope of that line would you view as demonstrating acceptable progress in reading comprehension.

Answer to Problem 17E

The slope of one is used.

Explanation of Solution

To measure progress in reading ability, the students at an elementary school take a reading comprehension test every year. Scores are measured in grade level units. The school principal prepares a report to parents that include a graph showing the mean recording score of each grade. The scatterplot of average reading level versus grade is given in the question. Therefore by looking at the data and the graph, we can say that a slope of one would indicate that for each one-year grade level increase, the average reading level is increasing by year. So, the slope of one of that line would we view as demonstrating acceptable progress in reading comprehension.