SOLUTION: Each time a bar of soap is used, its volume decreases by 10%. What is the minimum number of times a new bar would have to be used so that less than one-half its volume remains?

Question 287588: Each time a bar of soap is used, its volume decreases by 10%. What is the minimum number of times a new bar would have to be used so that less than one-half its volume remains?
(A) 5 (B) 6 (C) 7 (D) 8 (E) 9
Answer by CharlesG2(834) (Show Source): You can put this solution on YOUR website!
Each time a bar of soap is used, its volume decreases by 10%. What is the minimum number of times a new bar would have to be used so that less than one-half its volume remains?
(A) 5 (B) 6 (C) 7 (D) 8 (E) 9
new
0.9 * new (first use)
0.9 * 0.9 * new (second use) --> 0.81 * new
0.9^3 * new (3rd use) --> 0.729 * new
0.9^4 * new (4th use) --> 0.6561 * new
0.9^5 * new (5th use) --> 0.59049 * new
0.9^6 * new (6th use) --> 0.531441 * new
0.9^7 * new (7th use) --> 0.4782969 * new
C. 7

RELATED QUESTIONS
A jumbo chocolate bar with a rectangular shape measures 12 cm in length, 7 cm in width,... (answered by ikleyn)

A jumbo chocolate bar with a rectangular shape measures 12cm in length, 7cm in width, and (answered by josgarithmetic,ikleyn)

At the present time, a nutrition bar in the shape of a rectangular solid measures 0.75... (answered by stanbon)

A jumbo chocolate bar with a rectangular shape measures 12 centimeters in length, 7... (answered by ankor@dixie-net.com)

A jumbo chocolate bar with a rectangular shape measures 10 centimeters in length, 8... (answered by josgarithmetic,MathTherapy)

A jumbo chocolate bar with a rectangular shape measures 15centimeters in length,... (answered by josmiceli)

A jumbo chocolate bar with a rectangular shape measures 12 centimeters in length, 7... (answered by ikleyn,MathTherapy)

A candy company makes the popular Dandy Bar. The rectangular shaped bar is 10... (answered by nerdybill)

REDUCING THE SIZE OF A CANDY BAR a jumbo chocolate bar with a rectangular shape... (answered by MathTherapy)