Question

answer 10th question only​

Answer 1

Answer:

Given :

Trepezium PQRS as shown in the figure; also given PM = QM, PQ = 7 m, RS= 5m, the height of the tunnel is 2.4 m.The tunnel is 40m long , So

RS = MN = 5 m

And

PM = QN = 1 m

Total internal surface area excluding floor = Surface area of back of tunnel ( Shape of PQRS ) + RS× Length of tunnel + RQ × Length of tunnel + PS × Length of tunnel

Here , Height of tunnel = SM = RN = 2.4 m

We apply Pythagoras theorem in triangle PMS and get

PS2 = SM2 + PM2

PS2 = 2.42 + 12

PS2 = 5.76 + 1

PS2 = 6.76

PS2 = 2.62

PS = 2.6

We know Area of trapezium = Sum of parallel sides2× Height , So

Area of PQRS = 7 + 52× 2.6 = 122×2.6 = 6 × 2.6 = 15.6 m2

Then ,

Total internal surface area excluding floor = 15.6 + 5 × 40 + 2.6 × 40 + 2.6× 40 = 15.6 + 200 + 104 + 104 = 423.6 m2

Given , The rate of painting the internal surface of the tunnel (excluding the floor ) at Rs .5 per m2

Therefore ,

i ) The cost of painting the internal surface of the tunnel (excluding the floor ) = 423.6 × 5 = Rs . 2118 ( Ans )

And

Area of floor = PQ × Length of tunnel = 7 × 40 = 280 m2

Given , The rate of paving the floor at Rs .18 per m2

Therefore ,

ii ) The rate of paving the floor = 280 × 18 = Rs . 5040 ( Ans )

Hope this information will clear your doubts about Surface Areas and Volumes .

Answer 2

Answer:

hlo mates plz subscribe my channel wonderful maths and Quiz Tour