Solve the problem.How long will it take a sample of radioactive substance to decay to half of its original amount, if it decays according to the function A(t) = 250e-0.07t, where t is the time in years? Round to the nearest hundredth year.
A. 17.50 yr
B. 88.78 yr
C. 9.90 yr
D. 78.88 yr
Answer: C
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Solve the problem.Two recording devices are set 3600 feet apart, with the device at point A to the west of the device at point B. At a point on a line between the devices, 200 feet from point B, a small amount of explosive is detonated. The recording devices record the time the sound reaches each one. How far directly north of site B should a second explosion be done so that the measured time difference recorded by the devices is the same as that for the first detonation?
A. 1241.22 ft B. 1788.85 ft C. 425 ft D. 7375.64 ft
Find an equation of the line with the given slope that passes through the given point. Write the equation in the form 
m = - 
; (9, 0)
A. x + 9y = 4 B. x + 4y = 36 C. x + 4y = -9 D. x + 4y = 9
Find the requested angle.Supplement of 66°
A. 114° B. 294° C. 132° D. 24°
Evaluate dw.w = 4x2y + 4x3z;x = 3, y = 9, z = 6,dx = -0.02, dy = -0.01, dz = -0.01
A. -18.36 B. -17.64 C. -18.72 D. -5.76