The radioactive substance neptunium-139 decays to 73.64% of its original amount after 24 hours. How long (to the nearest hour) would it take for 39% of the original neptunium to be present?
?

A. 83 hr
B. 77 hr
C. 39 hr
D. 74 hr
E. 68 hr


Answer: D

Mathematics

You might also like to view...

Integrate the function.

A. 5 sin x + C
B. ln  + C
C.  ln  + C
D. 5 ln  + C

Mathematics

Solve for the variable.1.3x + 2.4 = 0.5x - 1.68

A. x = -0.196 B. x = -5.1 C. x = -5.61 D. x = -5.2

Mathematics

Write sigma notation.9 + 18 + 27 + 36 + 45 + . . .

A.
B.
C.
D.

Mathematics

Solve the problem.A boat is 180 feet from the base of cliff. If the distance from the top of the cliff to the boat is 45 more than twice the height of the cliff. Find the height of the cliff. Round to the nearest tenth of a foot if necessary.

A. 135 ft B. 75 ft C. 100.6 ft D. 45 ft

Mathematics