Quantitative Aptitude - Arithmetic Ability Questions

Suppose commodity X wil cost 40 paise more than Y after Z  years. Then,

        (4.20 + 0.40Z) - (6.30 + 0.15Z) = 0.40

=>  0.25Z = 0.40 + 2.10  => Z= 2.50/0.25 = 10

Therefore, X will cost 40 paise more than Y 10  years after 2001 . i.e in 2011

Let the speed of river and boat be 'r' m/min and 'b' m/min.
so relative speed in upstream (b-r)m/min and in downstream (b+r)m/min.
Now in upstream distnce covered in 5 min is 5(b-r)miles
so total distnce covered => 1 + 5(b-r)miles in upstream
In downstream distance covered in 5min is 5(b+r)miles
Now 1 + 5(b-r) = 5(b+r)
1+5b-5r = 5b+5r
1 = 10r
r = 1/10 mile/min => 6 mile/hr.

Numbers of students in section A = x
∴ Numbers of students in section B and C = (100 – x)
∴ x 70 + (100 – x) 87.5 = 84 100
=> 70x + 87.5 100 – 87.5x = 8400
=> 8750 – 17.5x = 8400
=> 17.5x = 8750 – 8400 => x = 20.

20 large cakes will require the equivalent of 10 helpers working for one hour. 700 small cakes will require the equivalent of 20 helpers working for one hour. This means if only one hour were available we would need 30 helpers. But since three hours are available we can use 10 helpers.

When the larger cube is cut into smaller cubes, the corner cubes will have paint on three sides. The cubes in the middle of the faces will have paint on only one side, but the cubes cut from the edges will have paint on two sides. In this case, there will be only one cube one each edge (excluding the corners), and since there are 12 edges, there will be 12 cubes with paint on two sides.

We can't determine the last day of the next month which has 31 days because we don't know the days in present month which may be 30 or 31. And the next month may be March which contains 31 days  which implies that the present month may be February which contains 28 or 29 days.

let each wheel make x revolutions per sec. Then2π*72*x+2π*7*x*10=19802*227*72*x+2*227*72*x=198

 66x=198 

distance moved by smaller wheel in 3 revolutions 

=2*227*72*3=66cm 

speed of smaller wheel = 663 m/s = 22m/s

Let the total amount in the partnership be 'x'.
Then A's share = x/3
B's share = x/4
C's share = x/5
D's share = x - (x/3 + x/4 +x/5) = 13x/60

A : B : C : D = x/3 : x/4 : x/5 : 13x/60 = 20 : 15 : 12 : 13

A's share in the profit of Rs. 2490 = 20 (2490/60) = Rs. 830.