# Post test HW ```Pg. 255/268 Homework
• Pg. 277 #32 – 40 all
Pg. 310 #1, 2, 7, 41 – 48
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#6
#24
#35
#1
#5
#7
#9
left 2, up 4
7
1



x= 8
2
Graph
Graph
Down 4
Right 3
Left 1, Up 7
7
2
#14 Graph
#28 x = 6
#51 r = 6.35, h = 9, V = 380
#3 a) dec b) inc c) dec
#6 Stretch 3
#8 Reflect x and y axes
#15 a = c
5.1 Exponential Functions
Life Span Problems
• The formula for Life Span
problems is similar to the
continuous growth/decay
equation using e.
• Population: 𝑆 = 𝑃𝑒 𝑟𝑡
• Life Span:
𝑦=𝑃 𝑎
𝑡
𝑑
• Suppose the half-life of a
substance is 20 days and
there are 5g present
initially.
– Write an equation to
represent the situation.
– Draw a complete graph.
– Find when there will be less
than 1g of the substance
remaining.
5.2 Simple and Compound Interest
Compound Interest
Example
• Compound Interest is when
financial institutions pay
interest on the interest.
(Yay… more money!)
• Sally invests \$500 at 7%
interest compounded annually.
Find the value of the
investment after 10 years.
• Suppose P dollars are invested
at an interest rate r, then the
compound interest formula
for the total amount S after n
interest periods is:
• How much should Sally
invested at 6.25%
compounded semi-annually in
order to have an investment of
\$1,500 after 5 years?
𝑟
𝑆 =𝑃 1+
𝑛
𝑛𝑡
5.2 Simple and Compound Interest
Compound Interest
• Sally invests \$1000 at 8%.
Find the value of the
investment after one year
when it is compounded
–
–
–
–
–
–
–
Annually
Quarterly
Monthly
Weekly
Daily
Hourly
Continuously
Continuous Interest
• If P dollars are invested at
an APR, r, (in decimal form)
and compounded
continuously, then the
value of the investment
after t years is given by:
S = Pert
```