## STAT 10

(Sec. 3a-3c)

Introduction to Statistical Reasoning

## Instructor: Ivo Dinov, Asst. Prof.

Departments of Statistics & Neurology
 http://www.stat.ucla.edu/~dinov/

Due Date:

# Friday, Oct.12, 2001, turn in at the end of lecture

See the HW submission rules. On the front page include the following header.

• (HW_2_1) Backpacks are commonly seen in many places, especially university campuses, schools, shopping malls and airplanes. In 1997, a US consumer magazine conducted a study on backpacks. Some of the data from the study is reproduced in the table below. The price of the backpacks is to the nearest US dollar, volume is measured in cubic inches and number of books is the number of 5-inch by 7-inch by half-inch books that the backpack easily holds.
• Calculate the average volume used per book (i.e. the volume divided by the number of books) for each backpack.
• Calculate the average the standard deviation of the backpack price, volume and number of books.
• What does the price distribution across manifacturers look like? Bell-shaped? Symmetric? Unimodal? Try to draw the price histogram using bins of size 5, starting at the mean.
• Write a short report (from 150 to 250 words) about the data. Your report should include a discussion on the data (comments on trends, problems or interesting features in the data and what other data could be collected to help consumers compare backpacks) and a recommendation for consumers (which backpack(s) do you recommend buying and why). Are we missing some factors that may effect our purchasing decision? If so, give examples.
 Backpack Code PM MM BL DS CM MR MP RP JC CB EW EA Price(\$) 38 40 50 48 35 35 45 50 35 95 40 40 Volume 1586 1810 2200 1874 1810 1950 1670 1500 1635 1102 1700 1500 Number of Books 47 44 48 50 49 49 49 40 73 38 49 50