Math 127 - Calculus I - Fall 98 Quiz 10

Ten thousand dollars is deposited into a saving account at 5% interest compounded continuously.

  1.   (2 points) What differential equation is satisfied by A(t), the balance after t years?

    (a) A'(t)= 5A(t)
    (b) A'(t)= 50A(t)
    (c) tex2html_wrap_inline65
    (d) A'(t)= .05A(t)

    Answer: (d)

  2. (2 points) How much money will be in the account after 10 years?

    (a) 1484131.59
    (b) 15579.55
    (c) 16288.95
    (d) 16487.21

    Answer: (d)

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  3. (2 points) When will the balance double?

    (a) 12.25 years
    (b) 13.86 years
    (c) 14.12 years
    (d) 23.87 years

    Answer:(b)

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  4. (2 points) How fast is the balance growing when it doubles?

    (a) 1000 dollars/year
    (b) 2000 dollars/year
    (c) 500 dollars/year
    (d) 20000 dollars/year

    Answer: (a) Using the differential equation in (1) we conclude that if at time tex2html_wrap_inline87 the ballance is tex2html_wrap_inline89 , then

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  5. (2 points) A different bank offers a saving account with interest compounded continuously. If the amount doubles after 10 years, the interest rate is approximately

    (a) 5.89%
    (b) 6.93%
    (c) 7.12%
    (d) None of the above

    Answer: (b)

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