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# Marathon runner

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A marathon runner drinks one bottle of sports drink for every 3 miles he runs, and the number of bottles he drinks as a function of the number of miles he runs can be described by the function B(m) = m/3. The cost of a bottle of sports drink is \$1.25, and the cost in dollars of the sports drink that the runner consumes as a function of the number of bottles he drinks can be described by the function C(b) = 1.25b. If the runner runs 24 miles, how much does the sports drink he consumes cost?

a) \$30

b) \$3.75

c) \$1.75

d) \$10

Jan 18, 2018

#1
+7350
+2

B(m) = m/3       ...this means...     number of bottles  =  m / 3

C(b) = 1.25b     ...this means...     cost  =  1.25( number of bottles )

So...   cost  =  1.25( m / 3 )

cost   =   1.25( 24 / 3 )   =   1.25( 8 )   =   10

Jan 18, 2018
#2
+17275
+3

The number of 3 mile 'sets' that he runs  is    24/3 = 8 'sets'   or 8 bottles of sports drink.

8 bottles  x  \$1.25 / bottle = \$10.00

Jan 18, 2018