Question

Madeline estimated the product of 3.56 and 8.3 below.

Answer 1

1.

C. The estimate is high because both factors are rounded up.

3.56 and 8.3 is rounded as 4*9. Rather it should have been rounded up like = 3.56 to 4 and 8.3 to 8 ; making $4\times8$=32

2.

Gasoline costs $3.65 a gallon. Round this to $4. To find the estimated cost of 14.2 gallons of gasoline, round this to 14.

So, cost becomes = $14\times4$ = $56

Option D is correct.

3.

Stu plans for the patio to be 12.5 feet by 18.3 feet.

Actual area becomes = $12.5\times18.3$ = 228.75 square feet

He orders enough brick for 247 square feet. Means he rounded off 12.5 to 13 and 18.3 to 19. Making $13\times19=247$ sq feet.

The correct option is A. Stu estimated correctly by rounding up. He ordered enough brick. The exact area is 228.75 square feet.

4.

Velvet fabric costs $11.49 a yard. Yvette buys 9.3 yards

Rounding 11.49 to 11.50 and 9.3 to 9, we get $11.50\times9=103.5$ or $104.

Option C is correct.

5.

As the values are rounded up and not down, the cost will be under $35. So, correct answer is option D .In step 4, he should have concluded the cost would be under $35.00

6.

$6.95 is rounded down to 6 and 9.5 is down to 9. This gives 54 which is too low. Rather it should be rounded up like $6.95 to 7 and 9.5 to 10 making it 7*10=70. So, option D is correct.

D.Sarah rounded $6.95 and 9.5 down. Her estimate of $54 is too low.

7.

Manuel buys 7.9 pounds of strawberries. Each pound costs $3.89.

Now rounding 7.9 to 8 and 3.89 to 4 , we get the best estimate. So, option A 8*4 is correct.

8.

The kitchen floor measures 11.3 feet by 9.25 feet.

The actual area is = $11.3\times9.25=104.525$ sq feet. But Kerrie had ordered tiles for only 99 sq feet which is very less. So, she estimated wrongly by rounding down the values. So, the correct answer is option D.

D. Kerrie did not estimate correctly by rounding down. She does not have enough tile. The exact area is 104.5 square feet.

Answer 2

The estimate is low because both factors are rounded up.