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

Explanation

Total surface area =` '2(lb + bh + hl)'`
Total surface area =` '2 (30 × 40 + 40 × 50 + 50 ×30)'`
Total surface area =` '9400 cm²`
•°• total surface area of one tin with dimension :`40 × 30 × 50` is `'9400sq.cm'`
Now multiply the total surface area of one tin with `'20'` tins.
Total surface area of `'20 tins = 20 × 9400=188000 cm^2²'`
As the cost of tin sheet is `'20 rs per m^2'` we need to change the unit of total surface area of `'20'` tins to m^2
`'1m² = (100 × 100)cm^2`
`1m^2= 10000 cm²'`
total surface area of '20' tins expresssd in m^2 is,
= `'188000/10000`
=`18.8m^2'`
Total surface area of `'20'` such tins `= '18.8m^2'`
cost of one square of tin sheet is `'20 rs per m^2`
•°• cost `'18.8m^2' `of tin sheet =` '20 ×18.8= 376'`
•°•cost of making `'20'` cuboid tins of dimension `'30cm × 40cm × 50cm'` is `'₹ 376.'`