A cuboidal oil tin is `30\ c m` by `40\ c m` by `50\ c mdot` Find the cost of the tin required for making `20\ ` such tines if the cost of tin sheet is `R s .20` per square metre.

Explanation

Given:
Length of the cuboidal oil tin `(l)=30cm`.
Breadth of the cuboidal oil tin `(b)=40cm`.
Height of the cuboidal oil tin `(h)=50cm`.
Cost of tin sheet is `Rs.20` per square metre.
Now, we will find the total surface area of `1` oil tin
`TSA=2(lb+bh+lh)`
`TSA=2{(30cmtimes40cm)+(40cmtimes50cm)+(30cmtimes50cm)}`
`TSA=2times(1200cm^2+2000cm^2+1500cm^2)`
`TSA=2times4700cm^2`
`TSA=9400cm^2`
Total surface area of `20` tins`=9400cm^2times20=188000cm^2=18.8m^2` `(1m^2=10000cm^2)`
Total cost for making `20` tins`=18.8timesRs.20=Rs.376`
Hence, cost required for making `20` tins is `Rs.376`.