Aptitude - Area - Discussion
Discussion Forum : Area - General Questions (Q.No. 15)
15.
A tank is 25 m long, 12 m wide and 6 m deep. The cost of plastering its walls and bottom at 75 paise per sq. m, is:
Answer: Option
Explanation:
| Area to be plastered | = [2(l + b) x h] + (l x b) |
| = {[2(25 + 12) x 6] + (25 x 12)} m2 | |
| = (444 + 300) m2 | |
| = 744 m2. |
 Cost of plastering = Rs. |
 |
744 x | 75 |  |
= Rs. 558. |
| 100 |
Discussion:
24 comments Page 1 of 3.
Tasrash said:
4 years ago
Forget the perimeter. the tank depth is 6m and it surrounded by 4 walls.
the two walls is 6x12 and another two walls is 6 x 25 in size.
So total wall area is= (2x6x12)+(2x6x25) = 444 sq m.
Now 4 walls completed plastering.
you have only the bottom side.
Area of bottom= 12x25 = 300 sq.m.
So Total area = 300 + 444 = 744 sq.m.
Now total cost is = 744 x 0.75 RS..
Draw a 3d sketch of a hollow rectangular pipe you will understand!
the two walls is 6x12 and another two walls is 6 x 25 in size.
So total wall area is= (2x6x12)+(2x6x25) = 444 sq m.
Now 4 walls completed plastering.
you have only the bottom side.
Area of bottom= 12x25 = 300 sq.m.
So Total area = 300 + 444 = 744 sq.m.
Now total cost is = 744 x 0.75 RS..
Draw a 3d sketch of a hollow rectangular pipe you will understand!
(19)
Avijit.AD said:
6 years ago
Thanks, @Salman.
That explanation is really easy to understand.
That explanation is really easy to understand.
Koks said:
6 years ago
How come 75/100?
(1)
Prayag said:
6 years ago
Hi Ben,
In the question, it is 75 Paise per sq. m and the option are in Rupees. So if you divide by 100 to convert 75 Paise to Rs i.e 0.75 Rs.
Therefore the answer is 744 sq.m. x Rs. 0.75 = Rs.558.
Thanks
In the question, it is 75 Paise per sq. m and the option are in Rupees. So if you divide by 100 to convert 75 Paise to Rs i.e 0.75 Rs.
Therefore the answer is 744 sq.m. x Rs. 0.75 = Rs.558.
Thanks
(2)
Ben said:
7 years ago
Why are we dividing 75 by 100? Please explain me.
MAS said:
8 years ago
Thanks A lot, @Salman. Your method is easiest.
Akbn said:
9 years ago
Yes, 558 is the correct answer.
Sivaprasad said:
9 years ago
I agree with you @Sundar.
I think what he said is right @All.
I think what he said is right @All.
Naimulsamad said:
9 years ago
Thanks to all. Now it's easy to understand.
Salman said:
10 years ago
The tank is open at the top so it has 5 sides. We have to calculate the area of the 5 sides including the bottom.
We have length l, breadth b and height h.
Area of bottom part = l*b.
Now for those remaining 5 sides the area will include h. So area of the remaining four sides is:
(l*h)+(b*h)+(l*h)+(b*h).
= 2(l*h)+2(b*h).
= 2(l+b)*h.
So total area of 5 sides is 2(l+b)*h+l*b.
We have length l, breadth b and height h.
Area of bottom part = l*b.
Now for those remaining 5 sides the area will include h. So area of the remaining four sides is:
(l*h)+(b*h)+(l*h)+(b*h).
= 2(l*h)+2(b*h).
= 2(l+b)*h.
So total area of 5 sides is 2(l+b)*h+l*b.
(8)
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