Discussion Room : Quant

@zabeer
Two trains start simultaneously from A and B towards B and A respectively at 8 a.m. They cross each other at 12 noon. Train starting from B, thereafter, takes 6 hrs to reach A. On a particular day the train starting from A, reduced its speed and arrived at B, 200 min late. At what time did the trains cross each other on that day?
A)1:00 pm
B)2:00 pm
C)1:30 pm
D) None of these


@zabeer
Find the volume of the solid obtained when the region bounded by y = √x, y = −x and the line x = 9 is revolved around the xaxis.Sir, according to me that will be a cone having radius=6 unit and height=9 unit. So the required volume will be 108π. But tell me the right approach....


A steel container is sold at Rs 120 cash or Rs 25 as cash down payment and Rs.25 a month for 4 months .The rate of interest per annum charged under the installment plan is .
(a) 26.09%
(b) 24.09%
(c) 20 %
(d) 23.25%Sir i have tried this way. Worth of Rs 95 after 4 months = 25 * [100 * 4+(R * 4 * 3)/100]
Please guide me

@zabeer
A,B and C start running along the circumference of a circle(circumference=1200 m) at the same time from the same point.A and B run in the clockwise direction with constant speeds of 8 m/s and 6 m/s respectively.C runs in the anticlockwise direction with a constant speed of 5 m/s.What is the time difference between the first two instances when C is equidistant from A and B along the circumference?
a)120 seconds b) 50 secs c)60 secs d) 100 secs
What's the procedure to solve this question?

120 rupees is the original price
25 rupees down payment means 95 rupees is what we are "Borrowing" from the shop.
Amount paid in instalments = 25 * 4 = 100
So 100  95 = 5 is the interest
Now this interest gained (Rs 5) is through the interest gained in the available amount month by month.
5 = 95R/(12 * 100) + 70R/(12 * 100) + 45R/(12 * 100) + 20R/(12 * 100)
5 = 230R/(12 * 100)
R = 6000/230 = 26.09%

Working together B and C take 50% more number of days than A, B and C together take and A and B working together, take 8/3 more number of days than A, B and C take together. If A, B and C all have worked together till the completion of the work and B has received Rs. 120 out of total earnings of Rs, 450, then in how many days did A, B and C together complete the whole work?

@vinaycat2017 Answer is 30 square units

In how many ways can distinct words of 5 letters each be made using the English alphabet?

@zabeer
A sphere passes through the midpoints of the twelve edges of a cube that has edges of length 6 inches. What is the surface area of the sphere, in square inches? Express your answer in terms of pi.