A = P(1+r/n)^<span>(nt)
1,687.30 = P (1+ 0.04/1)^3
1,687.30 = P (1.124864)
P = 1687.30 / </span>1.124864
P = 1500
answer: $1500 <span>was the original amount jeff invested</span>
This is a quadratic equation. There's a shortcut (two shortcuts really) called the Shakespeare Quadratic Formula (2b or -2b) applicable when the middle term is even:


OK, our problem is


Typically we'd write
but the answers here don't so we won't either.
Answer: C and D
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Information Given
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Find the difference
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Length of rope = 12 - 2 = 10ft
Vertical length of Kyle from the top of the rope when pulled to position is 10cos30° = 8.66 ft
Kyle's height of the ground = 12 - 8.66 = 3.34 ft