Joylin is writing an equation to model the proportional relationship between y, the total cost in dollars of downloading videos from a website, and x, the number of videos downloaded. she knows that the total cost to download 3 videos was $12. her work to find the equation is shown below. joylin’s work step 1 x=3/12=0.25 step 2 y=0.25x where did joylin make her first error? joylin divided 3 and 12 instead of multiplying the two numbers. joylin computed the decimal equivalent of 3/12 incorrectly. joylin used 0.25 as the coefficient of x instead of a product of x and y. joylin switched the numerator and the denominator when she found k.

Joylin is writing an equation to model the proportional relationship between y, the total cost in dollars of downloading videos from a website, and x, the number of videos downloaded. She knows that the total cost to download 3 videos was $12. Her work to find the equation is shown below. Joylin’s Work Step 1 x=3/12=0.25 Step 2 y=0.25x Where did Joylin make her first error? Joylin divided 3 and 12 instead of multiplying the two numbers. Joylin computed the decimal equivalent of 3/12 incorrectly. Joylin used 0.25 as the coefficient of x instead of a product of x and y. Joylin switched the numerator and the denominator when she found k.

Solution:

Joylin switched the numerator and the denominator when she found k.

Joylin should divide 12/3 and not 3/12. As, y is total cost and x is number of videos.

For x=1, number of videos=1, y,or total cost=1*4=4,

For x=2,y=2*4=8

For x=3, y=3*4=12

So, the constant, k=4

So, Option (D)

Joylin switched the numerator and the denominator when she found k.