Question

The sample data below are the typing speeds (in words per minute) and reading speeds (in words per minute) of nine randomly selected secretaries. Here, x denotes typing speed, and y denotes reading speed.
  

X	60	56	52	63	70	58	44	79	62
Y	587	551	528	607	645	531	503	652	571

At the 10% significance level, predict the reading speed for a typing speed of 74 words per  
minute.

Answer 1

	X	Y	X * Y	X2	Y2
	60	587	35220	3600	344569
	56	551	30856	3136	303601
	52	528	27456	2704	278784
	63	607	38241	3969	368449
	70	645	45150	4900	416025
	58	531	30798	3364	281961
	44	503	22132	1936	253009
	79	652	51508	6241	425104
	62	571	35402	3844	326041
Total	544	5175	316763	33694	2997543

Equation of regression line is Ŷ = a + bX


b = 4.879
a =( Σ Y - ( b * Σ X) ) / n
a =( 5175 - ( 4.8792 * 544 ) ) / 9
a = 280.079
Equation of regression line becomes Ŷ = 280.0791 + 4.8792 X

When X = 74
Ŷ = 280.079 + 4.879 X
Ŷ = 280.079 + ( 4.879 * 74 )
Ŷ = 641.12 ≈ 641