The following temperatures were recorded in Pasadena for a week in April: 87, 85, 80, 78, 83, 86, 90. Determine the interquartile range. Type a numerical answer in the space provided. Do not include spaces in your answer.

Find the median first.

78, 80, 83, 85, 86, 87, 90. The middle one is 85, so there's the median. Take the upper half of this set, not including the median, 85, and then subtract 86 from 90. This is 4, so this is the interquartile range.