In an attempt to estimate potential future demand, the National

Motor Company did a study asking married couples how many cars the

average energy-minded family should own in 1998. For each couple,

National averaged the husband's and wife's responses to get the overall

couple response. The answers were then tabulated:

Number of cars

0

0.5

1.0

1.5

2.0

2.5

Frequency

2

14

23

7

4

2

(a)Calculate the variance and the standard deviation.

(b) Since the distribution is roughly bell-shaped, how many of the

observations should theoretically fall between 0.5 and 1.5? Between 0 and

2? How many actually do fall in those intervals?