Step-1

Title: Surface area for Cone & Cuboid

Grade: 6-a Lesson: S3-L1

Explanation: Hello Students, time to practice and review the steps for the problem.

Lesson Steps

Step Type Explanation Answer

1

Problem

Determine the length and the lateral surface area of a cuboid whose lateral surface area is 880 sq. ft and whose breadth and height are 12 ft and 20 ft, respectively.

2

Step

The given values are

Lateral surface area = 880 sq.ft, h = 20 ft and w = 12 ft

3

Formula

The lateral surface area of the cuboid is

\$"Lateral surface area" = 2"h" ("w" + "l")\$

4

Step

So we can rearrange the formula to solve for l

\$"l" = (("lateral surface area")/(2"h")) - "w"\$

5

Step

Now plug the values in the formula

\$"l" = ((880)/2 times 20) - 12\$

6

Step

After simplification

⇒ l = 22 - 12
⇒ l = 10 ft

7

Formula

The total surface area of a cuboid is

\$"Total surface area" = 2"lw" + 2"lh" + 2"wh"\$

8

Step

Now plug the values in the formula

\$"Total surface area" = 2 times 10 times 12 + 2 times 10 times 20 + 2 times 12 times 20\$

9

Step

Make it simpler

\$"Total surfcae area" = 240 + 400 + 480\$

10

Step

After simplification

Total surfcae area = 1120 sq.ft

11

Step

So, the length of the cuboid is 1010 ft and the total surface area is 1120 sq. ft

12

SumUp

Can you summarize what you’ve understood in the above steps?

13

Choice.A

This is incorrect because it does not satisfies the conditions given in the problem

10 ft and 1210 sq.ft

14

Choice.B

This is incorrect because it does not satisfies the conditions given in the problem

10 ft and 1102 sq.ft

15

Choice.C

This is correct because it satisfies the conditions given in the problem

10 ft and 1120 sq.ft

16

Choice.D

This is incorrect because it does not satisfies the conditions given in the problem

10 ft and 1201 sq.ft

17

Answer

Option

C

18

SumUp

Can you summarize what you’ve understood in the above steps?


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