Question 1
A company keeps extensive records on its new salespeople on the premise that sales should increase with experience. A random sample of seven new salespeople produced the data on experience and sales shown in the table.

Summary statistics yield
SSxx = 94.8571,
SSxy = 124.7571,
SSyy = 176.5171,

= 5.8571, and

Calculate a 90% confidence interval for
E(
y) when

Assume

and the prediction equation is

Question 2
A realtor collected the following data for a random sample of ten homes that recently sold in her area.
House | Asking Price | Days on Market |
A | $114,500 | 29 |
B | $149,900 | 16 |
C | $154,700 | 59 |
D | $159,900 | 42 |
E | $160,000 | 72 |
F | $165,900 | 45 |
G | $169,700 | 12 |
H | $171,900 | 39 |
I | $175,000 | 81 |
J | $289,900 | 121 |
a. | Find a 90% confidence interval for the mean number of days on the market for all houses listed |
at $150,000.
b. | Suppose a house has just been listed at $150,000. Find a 90% prediction interval for the number |
of days the house will be on the market before it sells.