Q. If the price of a book is increased by 10% and the new price is $22, what was the original price?
A.$20
B.$18
C.$19
D.$21
Solution
Let the original price be x. The new price after a 10% increase is x + 0.1x = 1.1x. Setting this equal to $22 gives us 1.1x = 22, so x = 22/1.1 = 20. Therefore, the original price was $20.
Q. If the price of a book is increased by 10% and then decreased by 10%, what is the net change in price?
A.0%
B.1%
C.2%
D.3%
Solution
Let the original price be $100. After a 10% increase, the price becomes $110. After a 10% decrease, the price becomes $110 - $11 = $99. The net change is -1%, so the answer is 0%.
Q. If the price of a book is increased by 20% and then decreased by 20%, what is the net change in price?
A.0%
B.4%
C.5%
D.6%
Solution
Let the original price be Rs. 100. After a 20% increase, price = 120. After a 20% decrease, price = 120 - 24 = 96. Net change = (96 - 100)/100 * 100 = -4%.
Q. If the price of a book is increased by 20% and then decreased by 20%, what is the net change in the price?
A.0%
B.4%
C.5%
D.6%
Solution
Let the original price be $100. After a 20% increase, the price becomes $120. After a 20% decrease, the price becomes $120 - 0.20 × 120 = $96. The net change is (96 - 100)/100 × 100 = -4%.
Q. If the price of a shirt is increased by 20% and then decreased by 20%, what is the net change in the price?
A.0%
B.4%
C.5%
D.6%
Solution
Let the original price be 100. After a 20% increase, price = 120. After a 20% decrease, price = 120 - 24 = 96. Net change = (96 - 100)/100 * 100% = -4%.
Q. If the principal amount is $2000 and the total amount after 3 years at a certain rate of simple interest is $2400, what is the rate of interest? (2000)
A.5%
B.6.67%
C.10%
D.12%
Solution
The interest earned is $400. Using SI = PRT, we have 400 = 2000 * R * 3. Solving for R gives R = 6.67%.
Q. If the probability of event A is 0.2 and the probability of event B is 0.5, what is the probability of either A or B occurring if A and B are independent?
A.0.7
B.0.6
C.0.5
D.0.4
Solution
The probability of either A or B occurring is P(A) + P(B) - P(A and B) = 0.2 + 0.5 - (0.2 * 0.5) = 0.7.
Q. If the probability of event A is 0.4 and the probability of event B is 0.5, what is the probability of both A and B occurring if they are independent?
A.0.2
B.0.4
C.0.5
D.0.9
Solution
For independent events, P(A and B) = P(A) * P(B) = 0.4 * 0.5 = 0.2.
Q. If the probability of event C is 0.2 and the probability of event D is 0.3, what is the probability of either C or D occurring if they are mutually exclusive?
A.0.5
B.0.6
C.0.3
D.0.2
Solution
For mutually exclusive events, P(C or D) = P(C) + P(D) = 0.2 + 0.3 = 0.5.