Exponential Functions, Half-Life and Compound Interest

In an exponential function, what does the 'a' represent? 

• SLOPE
• RATE OF CHANGE
• Y-INTERCEPT
• COMMON RATIO

Is the pictured graph growth, decay, or linear or none?  

• Exponential Growth
• Exponential Decay
• Linear
• None

You invest $400 for 5 years and the interest rate is 4.29% each year. 

• y=400(1 - 0.0429)⁵
• y=400(1+.0429)⁵
• y=400(1+ 4.29)⁵
• y=400e^0.049*5

The value of a car is $15,000 and depreciates at a rate of 8% per year. What is the exponential equation?

• y=8(15,000)^x
• y=15,000(1 + .08)^x
• y=15,000(1 - .08)^x
• y=15,000(0.08)^x

You have inherited land that was purchased for $30,000 in 1960. The value of the land increased by approximately 5% per year. What is the approximate value of the land in the year 2011?

• $344,022
• $31,500
• $15,000
• $28,500

A particular radioactive element has a half life of 25 years. For an initial mass of 10 grams, the mass y in grams after t years is given by
y=10(1/2)^t/25 where t>0
How much does the mass remains after 120 years?

• .682
• .25
• .5
• .359

Johnny Frugal deposits $15,000 at the local bank. The bank offers 8% annual interest. How much will have he have after 6 years assuming all interest is reinvested (compound interest comes into play!)?

• $22,200
• $20, 241.21
• $24, 231.21
• $24, 241.21

Karla invested $1,000 in savings bonds. If the bonds earn 6.75% interest compounded semi-annually, how much total will Karla earn in 15 years?

• $1,584.62
• $2,651.39
• $2,706.86
• $1,825.10

Emily would like to buy some new furniture for her home. She decides to buy the furniture on credit with 9.5% interest compounded quarterly. If she spent $7,400, how much total will she have paid after 8 years.

• $15,415.94
• $15,683.28
• $15,927.56
• $16,109.05

Courtney saved up $2,200 working as a waitress over the summer. She put this money into a bank account that earned 5.2% interest and is compounded daily. How much will she have in her account at the end of 4 years?

• $2201.25
• $2694.55
• $2707.45
• $2708.63