Question

The following table gives age(x) in years of cars and annual maintenance cost(y) in hundred rupees:
x: 1 3 5 7 9
y: 15 18 21 23 22

Answer 1

Let a=5,b=8,c=1

Here n=4

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x¯¯¯=a+cu¯¯¯=a+c.∑un=5+1×04=5

y¯¯¯=b+cv¯¯¯=b+c.∑vn=8+1×0.54byx=bvu=n∑uv−∑u∑vn∑u2−(∑u)2=4(19.5)−(0)(−0.5)4(20)−(0)2=0.975

Regression equation of y on x is y−y¯¯¯=byx(x−x¯¯¯) is

Y–7.875=0.975(x−5)

Y=0.975x+3

When x=9

Y=0.975(9)+3

=11.775

Maintenance cost for a car 9 years old is 11.775×1000=11775 units