#### Solved Examples and Worksheet for Estimation-Percentages

Q1A man buys a Compact Stereo System for $135. The sales tax is 6%. Estimate the sales tax and the final cost. A.$143.1, $8.1 B.$8.1, $143.1 C.$8.1, $126.9 D.$6, $141 Step: 1 The sales tax is 6% of 135. Step: 2 6% = 6100 = 0.06 [Divide 6 by 100 to convert it into decimal.] Step: 3 Sales tax = 0.06 x 135 =$8.1
[Multiply the decimal by the cost of Compact Stereo System.]
Step: 4
Final cost = cost + sales tax = 135 + 8.1 = $143.1 [Add.] Step: 5 The sales tax on the Compact Stereo System is$8.1 and the final cost is $143.1. Correct Answer is :$8.1, $143.1 Q2Estimate 40% of 125. A. 96 B. 48 C. 144 D. None of the above Step: 1 40% of 125 [Expression to be evaluated.] Step: 2 = 820 of 125 [Rewrite 40% with an equal fraction 40100 or 820.] Step: 3 = 820 × 120 [Replace 125 with 120, which is compatible with the fraction.] Step: 4 = 81 × 6 [Cancel 120 with 20 .] Step: 5 = 48 [Simplify.] Step: 6 40% of 125 is 48. Correct Answer is : 48 Q3Estimate 48% of 70. A. 33 B. 37 C. 39 D. 35 Step: 1 48% of 70 [Original expression.] Step: 2 A fraction with denominator 2 is compatible with 70, as 70 is a multiple of 2. Step: 3 12 x 70 [Rewrite 48% as 50% or 50100 or 12.] Step: 4 = 35 [Cancel 70 with 2 and simplify.] Correct Answer is : 35 Q4Estimate 15.4% of 18. A. 2.5 B. 3.5 C. 4 D. 3 Step: 1 15.4% of 18 [Original expression.] Step: 2 320of 18 [Rewrite 15.4% as 15% or 15100 or 320.] Step: 3 320 x 20 [Replace 18 with 20 as it is compatible with the fraction.] Step: 4 = 32 x 2 [Cancel 20 and 20 with 10.] Step: 5 = 1.5 x 2 [Divide 3 by 2.] Step: 6 = 3 [Multiply.] Correct Answer is : 3 Q5Estimate 25% of 138. A. 30 B. 40 C. 25 D. 35 Step: 1 25% of 138 [Original expression.] Step: 2 = 14 of 138 [Write 25% as 25100 or 14.] Step: 3 14 x 140 [Since 140 is a multiple of 4, rewrite 138 as 140.] Step: 4 = 35 [Cancel 140 with 25 and simplify.] Correct Answer is : 35 Q6Estimate 32.4% of 900. A. 265 B. 275 C. 270 D. 260 Step: 1 32.4% of 900 [Original expression.] Step: 2 900 is a multiple of 10. So, a fraction with denominator 10 is compatible with 900. Step: 3 310 x 900 [Rewrite 32.4 as 30% or 30100 or 310.] Step: 4 = 270 [Cancel 900 with 10 and simplify.] Correct Answer is : 270 Q7John went out for a dinner. The bill was$38.93. Which of the following is a good estimate of a 20% tip on the bill?
A. $20.00 B.$3.50
C. $8.00 D.$15.00

Step: 1
20% of 38.93
[Expression to be evaluated.]
Step: 2
= 20100 of 38.93
[Rewrite 20% with an equal fraction 20100.]
Step: 3
= 20100of 40
[Replace 38.93 with 40, which is compatible with the fraction.]
Step: 4
= 15× 40
Step: 5
= 8
[Simplify.]
Step: 6
So, a good estimate of a 20% tip on the bill $38.93 is$8.
Q8Express 42 out of 100 as a percentage.

A. 42
B. 42%
C. 0.42
D. 32100

Step: 1
42 out of 100 is 42100 .
Step: 2
42 × 1100 = 42%
Step: 3
So, 42100 = 42%