MATH 123 EXAM 3 UPDATED ACTUAL QUESTIONS
WITH CORRECT ANSWERS
Question 1.
16.) Professor Ivy starts a Twitter account with 100 students as her followers. If her number of
followers doubles every month:
a.) How would you express her number of followers
as an exponential equation?
b.) How many followers would she have after 4 months?
c.) How many months would it take to reach
1,000,000 followers?
ANSWER
n=100(2)^t
b.)
n=100(2)^4 = 1600
c.)
I guessed 12 months and got 409,600, then I tried 18 months and got 26,214,400, so I tried 14
months and
got 1.6 million, 13 months is 819,200, so some time in between 13 and 14 months.
13.3
Question 2.
4.) If I invest $100 per month in a 401(k) at 1.5%
APR compounded monthly for 20 years, what would I enter into the formula below to determine by
balance at the end of the 20 years?
= FV(monthly interest rate, number of deposits, deposit amount)
ANSWER
= FV(.015/12, 12*20, 100)
Question 3.
5.) If your savings are growing at 3% per year, how long will it take for you to double your money?
ANSWER
70/3 = 23.33 years
1/7
, Question 4.
new book costs 27% more than a used book.
a.) A new book's price is ____ times the price of a used book?
b.) A used book is what percent of a new book?
ANSWER
new = 1.27*old, old = 1/1.27
* new, old = .787*new, The
used book is 78.7% of the price of a new book.
Question 5.
10.) The Kokomo Ivy Tech had 5,800 students enrolled in Fall 2012. This was down 10.7% from Fall
2011. About how many students must have been enrolled in Fall 2011?
ANSWER
new = (100 - 10.7)% x old,
5800 = .893*old, old = 6495 students in Fall 2011
Question 6.
12.) A club charges a $10 entrance fee and then charges $4.25 per drink.
a. Set up a Linear Model representing the cost of drinking at this club.
b.) What do your variables represent? Which is the independent? The dependent?
c. How much drinking can you do for $25?
ANSWER
y = 4.25x + 10
b.)
x is the number of drinks and is the independent, y is $ and is dependent.
c.)
x is the number of drinks and is the independent, y is $ and is dependent.
2/7
WITH CORRECT ANSWERS
Question 1.
16.) Professor Ivy starts a Twitter account with 100 students as her followers. If her number of
followers doubles every month:
a.) How would you express her number of followers
as an exponential equation?
b.) How many followers would she have after 4 months?
c.) How many months would it take to reach
1,000,000 followers?
ANSWER
n=100(2)^t
b.)
n=100(2)^4 = 1600
c.)
I guessed 12 months and got 409,600, then I tried 18 months and got 26,214,400, so I tried 14
months and
got 1.6 million, 13 months is 819,200, so some time in between 13 and 14 months.
13.3
Question 2.
4.) If I invest $100 per month in a 401(k) at 1.5%
APR compounded monthly for 20 years, what would I enter into the formula below to determine by
balance at the end of the 20 years?
= FV(monthly interest rate, number of deposits, deposit amount)
ANSWER
= FV(.015/12, 12*20, 100)
Question 3.
5.) If your savings are growing at 3% per year, how long will it take for you to double your money?
ANSWER
70/3 = 23.33 years
1/7
, Question 4.
new book costs 27% more than a used book.
a.) A new book's price is ____ times the price of a used book?
b.) A used book is what percent of a new book?
ANSWER
new = 1.27*old, old = 1/1.27
* new, old = .787*new, The
used book is 78.7% of the price of a new book.
Question 5.
10.) The Kokomo Ivy Tech had 5,800 students enrolled in Fall 2012. This was down 10.7% from Fall
2011. About how many students must have been enrolled in Fall 2011?
ANSWER
new = (100 - 10.7)% x old,
5800 = .893*old, old = 6495 students in Fall 2011
Question 6.
12.) A club charges a $10 entrance fee and then charges $4.25 per drink.
a. Set up a Linear Model representing the cost of drinking at this club.
b.) What do your variables represent? Which is the independent? The dependent?
c. How much drinking can you do for $25?
ANSWER
y = 4.25x + 10
b.)
x is the number of drinks and is the independent, y is $ and is dependent.
c.)
x is the number of drinks and is the independent, y is $ and is dependent.
2/7
