Answer:
(a) The least-square regression line is:
.
(b) The number of households using online banking at the beginning of 2007 is 31.8.
Step-by-step explanation:
The general form of a least square regression line is:

Here,
<em>y</em> = dependent variable
<em>x</em> = independent variable
<em>α</em> = intercept
<em>β</em> = slope
(a)
The formula to compute intercept and slope is:

The values of ∑<em>X</em>, ∑<em>Y</em>, ∑<em>XY</em> and ∑<em>X</em>² are computed in the table below.
Compute the value of intercept and slope as follows:

The least-square regression line is:

(b)
For the year 2007 the value of <em>x</em> is 10.
Compute the value of <em>y</em> for <em>x</em> = 10 as follows:


Thus, the number of households using online banking at the beginning of 2007 is 31.8.