Question

Cindy has 26 nickels. She is getting rolls of nickels from the bank. She has enough money to get up to 10 rolls of nickels and each roll contains 40 nickels. The bank will not give partial rolls. The function that models the number of nickels Cindy will have after leaving the bank is f(r)=40r+26, where r is the number of rolls of nickels she gets.
What is the practical domain of the function?



all real numbers

r>1

all integers from 1 to 10, inclusive

{66, 106, 146, 186, 226, 266, 306, 346, 386, 426}

Answer 1

We know that the domain is actually the number of rolls that she gets because it is the input variable in the equation  f (r) = 40 r + 26. The number of rolls that she can get can never be a negative number nor a zero nor a decimal number. However she can only get up to 10 rolls. Therefore the answer is:

 

all integers from 1 to 10, inclusive