Home › Functional Skills Maths Level 2 › Mathematics › Linear Rules and Rates of Change › A gym records the total paid against the length …
A gym records the total paid against the length of membership. Two months costs £74 and six months costs £158. How much does each extra month add?
A£26 per month
B£24 per month
C£19 per month
D£21 per month
Answer & Solution
Correct answer: D. £21 per month
1. Pair each length with its total: 2 months with £74, and 6 months with £158.
2. The total changes by £158 minus £74, which is £84.
3. The length changes by 6 months minus 2 months, which is 4 months.
4. Dividing £84 by 4 months gives £21 for each extra month.
5. Option A comes from dividing £158 by 6 months, which wrongly treats the joining fee as part of the monthly charge.
_Source: OpenStax College Algebra (CC BY 4.0), Ch 4 "Linear Functions", section 4.1 Linear Functions_
Related questions
A rule is built from the plain rule y = x by first making it steeper and then shifting it Two charges have exactly the same rate of change, but one adds an extra £15 to every totalA rule has a rate of change of 3 over 4. Starting from a plotted point, how do you step acWhen drawing a straight-line rule by working out points, two points are enough to draw theTwo straight lines have rates of change of 5 and minus 0.2. Multiplying the two rates togeOne line has a rate of change of 4. A second line crosses it at a right angle. What is theTwo tariffs are drawn on the same axes. They never meet, however far the lines are extendeA standing charge of £9 is added to a bill whatever the usage, so the amount stays at £9 a