A membership at Gym A costs $50 for 5 months. A membership at Gym B down the street costs $40 for 3 months. You write two equations in the form of y=kx

to try and figure out which membership would be cheaper for a year. What is the value of k
for the cheaper membership?

1 answer

To determine which gym membership is cheaper for a year, we need to find the total cost for each gym when considering their respective membership terms.

For Gym A: The cost is $50 for 5 months. To find the cost per month (k), we can express the cost for one month as follows:

\[ y_A = k_A x \]

where:

  • \( k_A = \frac{50}{5} = 10 \) (cost per month for Gym A)
  • \( x \) is the number of months

The cost equation for Gym A over 12 months (or 1 year) would be:

\[ y_A = 10x \] where \( x \) would be 12 months.

Now, to calculate the total cost for a year:

Since Gym A has an effective 5-month cycle, we solve:

\[ \text{Total for a year at Gym A} = \left(\frac{12}{5}\right) \times 50 = 2.4 \times 50 = 120 \]

For Gym B: The cost is $40 for 3 months. We express the cost for one month (k) similarly:

\[ y_B = k_B x \]

where:

  • \( k_B = \frac{40}{3} \) (approximately $13.33 per month for Gym B)
  • \( x \) is the number of months

The cost equation for Gym B over 12 months would be:

\[ y_B = \left(\frac{40}{3}\right)x \]

Now, to calculate the total cost for a year:

\[ \text{Total for a year at Gym B} = \left(\frac{12}{3}\right) \times 40 = 4 \times 40 = 160 \]

Now we compare the yearly totals for both gyms:

  • Total for Gym A for one year: $120
  • Total for Gym B for one year: $160

Since Gym A is cheaper, the value of \( k \) for the cheaper membership (Gym A) is:

\[ \boxed{10} \]