SURFACE AREAS AND VOLUMES571a A classroom is 7 m long, 6.5 m wide and

1.	SURFACE AREAS AND VOLUMES571a A classroom is 7 m long, 6.5 m wide and 4 m high. It has one door 3 m x 1.4 m and three windowseach measuring 2 m Ă 1 m. The interior wall is to be colour washed. Find the cost of colorwashing at the rate ofm2 is R 17550 and the cost of papering the walls at t 140 per m is R 24080. Find the dimensionsof the room.An open box is made of wood 3 cm thick. Its external dim3.50 per m2ICBSE 2012]13. Length of a room is one and a half time of its breadth. The cost of carpeting the room at ? 325 perCBSE 2016]14.
Answer» 12)Area of four walls=(2h(l+b))=(2x4(7+6.5))=(8x13. 5)=108m squarearea of one window =3mx1. 4m=4.2m squarearea of three window =3(2mx1m)=6m squaretotal area of windows =(4.2+6)m square=10.2m squareArea for whitewashing =(108-10.2)m square=97.8m square cost of 1 m square white washing = 3.50rupeecost of 97.8m square white washing=3.50x97.8=342.3 rupees 13)Solution :- Let the breadth of the room be b .Then, length of the room l = 1.5 bArea carpeted by Rs 3.25 = 1m²area carpeted with Rs 175.50 is the area of the floor.the area of the floor = 1 / 3.25 × 175.50 = 54 m²therefore lb=54(1.5b) × b=541.5b²= 54b² = 54/ 1.5 = 36b = 6m.therefore, the breadth of the room is 6 m.length of the room =1.5× 6= 9 mlet the height of the room be h m.area of the walls = 2h ( l + b ) = 2h ( 9+6) = 30hm²since 1 door and 2 windows occupy 8 meter square.therefore area of papering =30h-8 meter square......(1)cost of papering the walls at Rs. 1.40 per m2 is Rs. 240.80.therefore area of papering = 240.80/ 1.40 = 172m²Now, from the eqn 1 ...........30h - 8 = 17230h = 180 h= 180/ 30= 6m.therefore, the height of the room is 6 m.hence the dimensions of the room is 9× 6 ×6.

SURFACE AREAS AND VOLUMES571a A classroom is 7 m long, 6.5 m wide and 4 m high. It has one door 3 m x 1.4 m and three windowseach measuring 2 m Ă 1 m. The interior wall is to be colour washed. Find the cost of colorwashing at the rate ofm2 is R 17550 and the cost of papering the walls at t 140 per m is R 24080. Find the dimensionsof the room.An open box is made of wood 3 cm thick. Its external dim3.50 per m2ICBSE 2012]13. Length of a room is one and a half time of its breadth. The cost of carpeting the room at ? 325 perCBSE 2016]14.

Answer»

12)Area of four walls=(2h(l+b))=(2x4(7+6.5))=(8x13. 5)=108m squarearea of one window =3mx1. 4m=4.2m squarearea of three window =3(2mx1m)=6m squaretotal area of windows =(4.2+6)m square=10.2m squareArea for whitewashing =(108-10.2)m square=97.8m square cost of 1 m square white washing = 3.50rupeecost of 97.8m square white washing=3.50x97.8=342.3 rupees

13)Solution :-

Let the breadth of the room be b .Then, length of the room l = 1.5 bArea carpeted by Rs 3.25 = 1m²area carpeted with Rs 175.50 is the area of the floor.the area of the floor = 1 / 3.25 × 175.50 = 54 m²therefore lb=54(1.5b) × b=541.5b²= 54b² = 54/ 1.5 = 36b = 6m.therefore, the breadth of the room is 6 m.length of the room =1.5× 6= 9 mlet the height of the room be h m.area of the walls = 2h ( l + b ) = 2h ( 9+6) = 30hm²since 1 door and 2 windows occupy 8 meter square.therefore area of papering =30h-8 meter square......(1)cost of papering the walls at Rs. 1.40 per m2 is Rs. 240.80.therefore area of papering = 240.80/ 1.40 = 172m²Now, from the eqn 1 ...........30h - 8 = 17230h = 180 h= 180/ 30= 6m.therefore, the height of the room is 6 m.hence the dimensions of the room is 9× 6 ×6.

Discussion

No Comment Found

Related InterviewSolutions

Reply to Comment