ECON 220 (4)

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Quant Tools for Bus & Econ – ECON 220-02 (11273)

Homework 4

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Section 0.2

Evaluate the expressions in Exercises 1-4 (2 points each)

1. 2 ∙ 80 = ________

2. (4 ∙ 2)2 = ______________

3. −2−3 = ________________

4. 52 ∙ 5−3 ∙ 52 ∙ 5−2 =__________________

Simplify each expression, expressing each answer in rational form (2 points each)

5. −𝑥𝑦−1𝑥−1 =

6. ( 𝑥2𝑦−1𝑧0

𝑥𝑦𝑧 ) 2

=

7. ( 𝑥𝑦−2

𝑥2𝑦−1𝑧 ) −3

=

Convert the expression below to rational form (2 points)

8. 1

2 𝑥−4 = _________________

2

Convert the expression below to exponent form (1 point each)

9. √8 = _____________

10. √𝑥2 3

= _____________

Section 9.2

For each function, compute the missing values in the table (3 points)

x -3 -2 -1 0 1 2 3

𝑓(𝑥) 𝑔(𝑥) 𝑟(𝑥)

11. 𝑓(𝑥) = 3−𝑥

12. 𝑔(𝑥) = 𝑒𝑥/5

13. 𝑟(𝑥) = 50 (1 + 1

3.2 ) 2𝑥

14. Model the data using an exponential function 𝑓(𝑥) = 𝐴𝑏𝑥 (4 points)

x 0 1 2

𝑓(𝑥) 500 1000 2000

x 0 1 2

𝑔(𝑥) 90 30 10

_________________________________

____________________________

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Section 2.2 15. In March 2010, a Bank was offering 2.4% interest on its savings account with interest

reinvested quarterly.

a. Find the associated exponential model for the value of a $4,000 deposit after t years

(1 point)

b. Assuming this rate of return continued for eight years, how much would a deposit

of $4,000 in March 2010 be worth in March 2018? (1 point)

c. Assuming this rate of return continued for ten years, how much would a deposit of

$4,000 in March 2010 be worth in March 2020? (1 point)

16. MyCompany.com is offering a savings account that pays 31% interest compounded

continuously. How much interest would a deposit of $2,000 earn over 10 years? (2 points)