The volume of the lunch box is 300 cubic m and the area of the upper face is 20sq m The total surfac...........

Quantitative Aptitude (CDS) Mensuration 2D

The volume of the lunch box is 300 cubic m and the area of the upper face is 20sq m. The total surface area of the lunch box is 490sq m find the approximate value of length, breadth, and height of the lunch box?

13m,14m,12m

1.5m ,3.5m ,7m

15m ,13.5m ,2.5m

1.5m ,13.5m ,15m

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Explanation:

let l,b, and h be the length, breadth, and height of the lunch box
given
l×b×h=300 m^3.....1
2(lb + bh + hl)=490 m^2....2
lb=20m^2.....3
from 3 and 1 we get
h=15m
on putting value of h in 2 we get
20+h(b+l)=245
=h(b+l)=225
=(b+l)=15.....4
now
(b-l)^2=(b+l)^2 -4bl
=(15)^2-4×20
=225-80
=145 sq m
b-l~12....5
adding 4 and 5 we get
2b=27
b=13.5 m
from 4
l=1.5 m