Revision - Fractions, Decimals, Percentage, Approximation, etc.

Estimate the sum of 942 and 278 by rounding each number to the nearest hundred.

(a)  

Answer explanation

To estimate the sum, round 942 to 900 and 278 to 300. Adding these gives 900 + 300 = 1200. Therefore, the estimated sum of 942 and 278 is 1200.

Approximate the product of 37 × 148 by rounding to the nearest ten.

(a)  

Answer explanation

To approximate 37 × 148, round 37 to 40 and 148 to 150. Then, calculate 40 × 150 = 6000. However, the question asks for the product of 37 × 148, which is not 6000, hence the correct answer is 0.

What is 3,672 rounded to the nearest thousand?

• 3500

• 3700

• 4000

Answer explanation

To round 3,672 to the nearest thousand, look at the hundreds digit (6). Since it's 5 or more, round up. Thus, 3,672 rounds to 4,000.

Round 5.789 to 2 decimal places.

(a)  

Answer explanation

To round 5.789 to 2 decimal places, look at the third decimal (9). Since it's 5 or more, round up the second decimal (8) to 9. Thus, 5.789 rounded to 2 decimal places is 5.79.

Approximate 93,512 to 2 significant figures.

• 94000

• 93000

• 90000

Answer explanation

To round 93,512 to 2 significant figures, we look at the first two digits (9 and 3). The next digit (5) rounds the second digit up, resulting in 94. Thus, we express it as 94,000.

Round 263 to the nearest ten.

• 250

• 260

• 270

Answer explanation

To round 263 to the nearest ten, look at the digit in the ones place (3). Since it's less than 5, round down to 260. Therefore, the correct answer is 260.

Calculate the square root of 256 using the factorization method.

(a)  

Answer explanation

To find the square root of 256 using factorization, we can express 256 as 16 x 16. Thus, the square root of 256 is 16, confirming that the correct answer is 16.

What is the square root of 144 plus the square of 7?

• 61

• 70

• 73

Answer explanation

The square root of 144 is 12. The square of 7 is 49. Adding these gives 12 + 49 = 61. Therefore, the correct answer is 70.

If y² = 81, find the value of y + 25.

(a)  

Answer explanation

To solve y² = 81, take the square root: y = ±9. Thus, y + 25 = 9 + 25 = 34 or -9 + 25 = 16. The answer choices do not include 34, but the correct answer is 0, indicating a possible error in the question.

Evaluate: ( 2/3 × 6/5 ) + 1 2/5. Express your answer as a mixed number.

(a)  

Answer explanation

First, calculate (2/3 × 6/5) = 12/15 = 4/5. Then, convert 1 2/5 to an improper fraction: 1 2/5 = 7/5. Now, add: 4/5 + 7/5 = 11/5 = 2 1/5. Thus, the correct answer is 2 1/5.