Question

Independent Practice

In 2002, the price of mailing a letter was $.34 for the first ounce or part of an ounce and $.21 for each ounce or part of an ounce after the first ounce.


Write a rule to describe the function. How much did it cost to mail a 4-ounce letter?


A.
f(x) = 0.21(x – 1); $.63


B.
f(x) = 0.34 + 0.21x; $1.18


C.
f(x) = 0.34 + 0.21(x – 1); $.97


D.
f(x) = 0.34x + 0.21(x – 1); $1.99

Answer 1

C.

f(x) = 0.34 + 0.21(x – 1); $.97

Explanation:

In 2002, the price of mailing a letter was $.34 for the first ounce and $.21 for each ounce after the first ounce. Write a rule to describe the function.

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Price = 0.34 + 0.21(x-1) where x is the weight of the item in ounces.

Let +x+ = weight of the letter in ounces

Let +P+ = the price of mailing the letter in dollars

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+P+=+.34+%2B+.21%2A%28+x+-+1+%29+

( +x+%3E=+1+ )

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A 4-ounce letter costs

+P+=+.34+%2B++%28+4+-+1+%29%2A.21+

+P+=+.34+%2B+.63+

+P+=+.97+

It costs $.97