Quantitative Aptitude - Arithmetic Ability Questions

Total quantity of petrol consumed in 3 years =(4000/7.50+4000/8+4000/8.50)  liters

                                                         = 4000(2/15+1/8+2/17) liters                                                   

                                                         = 76700/51 liters

Total amount spent = Rs. (3 x 4000) = Rs. 12000.

Average cost = Rs. (12000*51/76700) = Rs. 7.98.

Let 1 woman's 1 day work = x.

Then, 1 man's 1 day work = x/2 and 1 child's 1 day work  x/4.

So, (3x/2 + 4x + + 6x/4) = 1/7

28x/4 = 1/7 => x = 1/49

1 woman alone can complete the work in 49 days.

So, to complete the work in 7 days, number of women required = 49/7 = 7.

Since it is an isosceles trapezium

So angle C = angle D = x

let A = 180 –D = 180 –x (since AB is parallel to CD)

B = 180-x

A+C = 180 –x + x = 180 degrees (Property of cyclic quadrilateral)

ABCD is cyclic parallelogram with AB // CD and AD // BC

Considering angles A = C = y (Property of parallelogram) and B=D = x Also since it is cyclic A+C = B+D = 180 degrees

So x=y=90 degrees And also opposite sides are equal being a parallelogram

Thus ABCD is a rectangle