Q. 54.1( 15 Votes )
A field is in the shape of a trapezium having parallel sides 90 m and 30 m. These sides meet the third side at right angles. The length of the fourth side is 100 m. If it costs Rs 4 to plough 1m2 of the field, find the total cost of ploughing the field.
PQ = 90m
RS = 30m
QR = 100m
PQ = PT + TQ = 90m
⇒ 30 + TQ = 90
⇒ TQ = 60
QR2 = TR2 + QT2
⇒ 1002 = TR2 + 602
⇒ TR2 = 10000-3600
⇒ TR2 = 6400
⇒ TR = 80m
Area (PQRS) =
Area(PQRS) = 60 × 80 = 4800 m2
Cost of ploughing = Area(PQRS) × Cost per m2
∴ Cost of ploughing = 4800 × 4 = Rs. 19200.
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