Question

Mr. James McWhinney, president of Daniel-James Financial Services, believes there is a relationship between the number of client contacts and the dollar amount of sales. To document this assertion, Mr. McWhinney gathered the following sample information. The X column indicates the number of client contacts last month, and the Y column shows the value of sales ($ thousands) last month for each client sampled. (Round the final answers to 2 decimal places.)

Number of
Contacts,
X   Sales
($ thousands),
Y   Number of
Contacts,
X   Sales
($ thousands),
Y  
14   $24   23   $30  
12   14   48   90  
20   28   50   85  
16   30   55   120  
46   80   50   110  
b. Suppose a large sample is selected (instead of just 10). About 95% of the predictions regarding sales would occur between what two values? Assuming that the Standard Error of Estimate does not change. Use z = 2.

Answer 1

X	Y
14	24		mean	61.1
12	14		Std. Dev	39.78959
20	28		Z	2
16	30		n	10
46	80		Std. Dev/sqrt(n)	12.58257
23	30
48	90		Z*SE	25.16514
50	85
55	120		lower	35.93486
50	110		upper	86.26514

Ans: Please look at the table for values

For the population, about 95% values fall between

Based on the sample,

z is given as 2

n = 10

Standard error = SE =

Hence, the range= [61.1 - 2*12.58 , 61.1 + 2*12.58]

= [35.93, 86.26]