math

posted by .

According to the center of Science in the Public Interest, the maximum healthy weight for a person who is 5 feet, 5 inches is 150 pounds and the maximum healthy weight for a person 6 feet, 3 inches tall is 200 pounds. The relationship between weight and height is linear.

When I saw the word LINEAR, I immediately thought about y = mx + b.

Find an equation that gives the maximum healthy weight y for a person whose height is x inches over 4 feet, 10 inches.

HINTS GIVEN IN MATH BOOK:

x = 0 represents a person 4 feet, 10 inches
x = 2 represents a person 5 feet tall, etc.

The correct equation is y = 5x + 115. I was able to find the slope 5 and got as far as y = 5x. My question is: where did 115 come from?

I look forward to your insight and guidance.

Thanks

  • math -

    5 ft, 5 inches = 5.4166667 feet
    6 ft, 3 inches = 6.25 feet

    so I look at the given data as 2 ordered pairs,
    (5.4166667 , 150) and (6.25 , 200)

    slope = (200-150)/(6.25-5.4166667) = 60

    so y = 60x + b
    using the point (6.25,200)

    so a person 4 ft 10 inches tall or 4.8333333 ft should weigh

    y = 4.8333333(60) - 175 = 115 lbs

    I really do not understand their hint.
    200 = 60(6.25) + b
    b = -175

    so my equation is
    y = 60x - 175 , where x is feet and y is lbs.

    checking the other point
    if x = 5.4166667
    y = 60(5.4166667) - 175 = 150

    my equation works for both data values.

  • math -

    Thank you. I also played with this question some more and learned that
    y = 5x - 175 works just the same. You said the slope is 60 but 60 inches divided by 12 inches = 5 feet. I decided to use 5 for the slope.
    Both equations work very well.

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. math

    Can you tell me if I have the correct answer to this problem. A formula to determine the area of a person’s skin in square inches is s=15.7w^0.425 h^0.725 where w is weight in pounds and h is height in inches. Use S to estimate the …
  2. Applied Calculus

    For the average person that is still growing, the rate of change in weight W (in pounds) with respect to height h (in inches) is approximately dW/dh=0.0015h^2 pounds per inch. Suppose that the average person that is 60 inches tall …
  3. math

    For a person of height h (in inches), a healthy weight W (in pounds) is one that satisfies this system of inequalities: W is greater than or equal to (19h^2)/703 and W is less than or equal to (25h^2)/703 Graph the system for 0 is …
  4. Math

    If Sally places a rocket that is 3 feet 6 inches tall atop a launch pad that is 1 foot 8 inches tall, how tall will the entire unit, rocket and launch pad, be when she is done?
  5. Geometry

    A person who is 5 feet, 6 inches (5.6 feet) tall casts a shadow (from N to S) that is 12 feet long. The distance along the ground from the person (N) to the flagpole (G) is 18 feet. Find the height of the flagpole (FG) showing all …
  6. Algebra

    Suppose that the maximum weight that a certain type of rectangular beam can support varies inversely as its length and jointly as its width and the square of its height. Suppose also that a beam 6 inches wide, 2 inches high, and 12 …
  7. Algebra

    Suppose that the maximum weight that a certain type of rectangular beam can support varies inversely as its length and jointly as its width and the square of its height. Suppose also that a beam 6 inches wide, 2 inches high, and 12 …
  8. Mathematics

    Suppose that the maximum weight that a certain type of rectangular beam can support varies inversely as its length and jointly as its width and the square of its height. Suppose also that a beam 4 inches wide, 3 inches high, and 18 …
  9. Math

    The normal weight (w) in pounds of a male between 60 and 70 inches tall is related to his height (h) in inches and is represented by w=11/2h-220, if a boy weight 145 pounds, how tall is he?
  10. algebra

    Three boxes are stacked one on top of the other. One box is 2 feet 8 inches tall, one is 4 feet 7 inches tall, and one is 3 feet 11 inches tall. How high is the stack?

More Similar Questions