What does the 6 in the tractor maker's trend y…

What does the 6 in the tractor maker's trend y = 120 + 6x mean?

Question 51

EasyOriginal question

A tractor maker fits the trend $y = 120 + 6x$ to its yearly sales, where $y$ is sales in thousands and $x$ is years counted from 2020 ( $x = 0$ in 2020).

What does the 6 in the tractor maker's trend $y = 120 + 6x$ mean?

Sales rise by about 6 thousand tractors a yearCorrect answerYour answerSales rise by 6% a yearCorrect answerYour answerSales were 6 thousand tractors in 2020Correct answerYour answerThe trend covers 6 years of dataCorrect answerYour answer

Show the answer and explanation

CorrectNot quiteAnswer A

Correct answer: A

6 is the slope: each extra year adds 6 to $y$ .
$y$ is in thousands, so about 6 thousand tractors a year.

Worth noting

A straight-line trend adds a fixed amount each year, not a fixed percentage.

Concept: The meaning of the slope
Typical timeTypical: 90 s
Your timeYours: —

The rule this testsA straight-line trend by least squares

Practise this chapter →

Ten questions from Time Series & Trend, at your own pace.

Practise this chapter →

Ten questions from Time Series & Trend, at your own pace.

What does the 6 in the tractor maker's trend y = 120 + 6x mean?

Question 51

Explanation