Question

For y = 25, what is the estimated value of x, from the following data x 11 12 15 16 18 19 21 y 21 15 13 12 11 10 9​

Answer 1

Given that,

The following data,

x = 11, 12, 15, 16, 18, 19, 21

y = 21, 15, 13, 12, 11, 10, 9

We know that,

The general equation of best fit line.

$y=mx+b$

We need to calculate the value of m and b

Using given data

We use graphing calculator then,

We get the value of m and b

$m = -1.0125$

$b=29.2$

We need to calculate the linear equation

Using linear equation

$y=mx+b$

Put the value of m and b

$y=-1.0125x+29.2$...(I)

We need to calculate the value of x

Using equation (I)

$y=-1.0125x+29.2$

Put the value of y = 25

$25=-1.0125x+29.2$

$1.0125x=29.2-25$

$x=\dfrac{29.2-25}{1.0125}$

$x=4.14$

Hence, The value of x is 4.14.