Lesson Example Discussion Quiz: Class Homework |
Step-5 |
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 |
A rectangular box with dimensions of 15 cm in length, 8 cm in width, and 10 cm in height. If the height is increased by 4 cm, what is the new surface area? |
|
2 |
Step |
The given values are |
l = 15 cm , w = 8 cm and h = 10 cm and |
3 |
Formula |
The surface area is |
\$"Surface area" = 2"lw" + 2"lh" + 2"wh"\$ |
4 |
Step |
Now plug the values in the formula |
\$"Surface area" = 2 times 15 times 8 + 2 times 15 times 10 + 2 times 8 times 10\$ |
5 |
Step |
After simplification |
\$"Surface area" = 240 + 300 + 160\$ |
6 |
Step |
Make it simpler |
Surface area = 700 sq.cm |
7 |
Tip |
Now, if we increase the height by 4 cm: New height = 10 cm + 4 cm = 14 cm |
|
8 |
Step |
The new surface area will be calculated using the new height |
\$"Surface area_new" = 2"lw" + 2"l"("new height") + 2"w"("new height")\$ |
9 |
Step |
Now plug the values in the formula |
\$"Surface area _new" = 2 times 15 times 8 + 2 times 15 times 14 + 2 times 8 times 14\$ |
10 |
Step |
After simplification |
\$"Surface area" = 240 + 420 + 224\$ |
11 |
Step |
Make it simpler |
Surface area = 884 sq.cm |
12 |
Step |
So, the new surface area of the rectangular box, after increasing the height by 4 cm, is 884 sq. cm |
|
13 |
SumUp |
Can you summarize what you’ve understood in the above steps? |
|
14 |
Choice.A |
This is wrong because it does not match the calculated new surface area |
844 sq.cm |
15 |
Choice.B |
This is wrong because it does not match the calculated new surface area |
800 sq.cm |
16 |
Choice.C |
This is wrong because it does not match the calculated new surface area |
818 sq.cm |
17 |
Choice.D |
This is correct because it match the calculated new surface area |
884 sq.cm |
18 |
Answer |
Option |
D |
19 |
SumUp |
Can you summarize what you’ve understood in the above steps? |
|
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