Find the principle needed now

Find the principle needed now to get the given amount; that is find the present value.

$80 after 1 1/4 years at 6% compounded continuously.

80 = P x (1 + 6/36500)^(365 x 1.25)

=> 80 = P x (1.000164384)^456.25

i.e. P = $74.22

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use the compund interest formula

A = P[1 + r]^t

A = final amount
P = starting amount [principal]
r = rate in decimal form [ 6% = 6/100 = .06]
t = time

80 = P[1+.06]^1.25

80/1.07555 = P

principal = $74.38

A = Pe^(rt)
80 = Pe^(.06 * 1.25)
80 / e^.075 = P
74.219478906284231377339436757169 = P
$74.22 = P