Finding an Estimate for Interquartile Range

The video tutorial explains how to use a cumulative frequency graph to estimate the interquartile range and analyze film lengths. It covers calculating the interquartile range by identifying upper and lower quartiles and determining the percentage of films over 120 minutes. The tutorial also includes verifying a claim about the percentage of films exceeding a certain length.

What is the purpose of using a cumulative frequency graph in this context?

• To find the mean of the data set

• To determine the median directly

• To estimate the interquartile range

• To calculate the mode of the data

How do you determine the upper quartile from a cumulative frequency graph?

• By finding 1/2 of the total frequency

• By locating 3/4 of the total frequency

• By calculating 1/4 of the total frequency

• By identifying the maximum frequency

What is the interquartile range if the lower quartile is 103 and the upper quartile is 123?

• 25 minutes

• 20 minutes

• 15 minutes

• 10 minutes

What does Clare claim about the films?

• More than 35% are over 120 minutes

• Exactly 35% are over 120 minutes

• More than 50% are over 120 minutes

• Less than 35% are over 120 minutes

How many films are over 120 minutes long according to the graph?

• 25 films

• 30 films

• 35 films

• 40 films

What percentage of films are over 120 minutes long?

• 45%

• 40%

• 35%

• 31.25%

Why is Clare's claim about the percentage of films incorrect?

• Because 55 out of 80 films is 35%, not 31.25%

• Because 55 out of 80 films is 31.25%, not 35%

• Because 25 out of 80 films is 35%, not 31.25%

• Because 25 out of 80 films is 31.25%, not 35%