Quantitative Aptitude - Arithmetic Ability Questions

let 't' be the time after which they met since L starts.

Given K is 50% faster than L

50 t + 1.5*50(t-1) = 300

50 t +75 t = 300 + 75

t = 375 / 125 = 3 hrs past the time that L starts

So they meet at (9 + 3)hrs = 12:00 noon.

Let the distance in one direction = k kms

Speed in still water = 4.5 kmph

Speed of river = 1.5

Hence, speed in upstream = 4.5 - 1.5 = 3 kmph

Speed in downstream = 4.5 + 1.5 = 6 kmph

Time taken by Rajesh to row upwards = k/3 hrs

Time taken by Rajesh to row downwards = k/6 hrs

Now, required Average speed =$$\begin{gathered} Total distanceTotal speed = 2kk3 + k6 \\ = 2k x 186k + 3k = 4 kmph \end{gathered}$$ 

Therefore, the average speed of the whole journey = 4kmph.

Let the third subject marks be 'x'
=> Second subject marks = 2x
=> Third subject marks = 4x
Given avg = 224
x + 2x + 4x = 224 x 3
=> 7x = 224 x 3
=> x = 96
Hence, Second subject marks = 2x = 2 x 96 = 192.

Let the inner and outer radii be r and R metres.

Then  2πR=3527=>R=3527*722*12=8m 

 2πR=5287=>R=5287*722*12=12m

=> Width of the ring = (R - r) = (12 - 8) m = 4 m.

Given,Let the cost price of single book be Rs. 100.

The cost price of (9 + 1) = 10 pair i.e. 20 books = Rs. (100 × 20) = Rs. 2000.He gets profit of 26%.

So, the selling price of 9 pair i.e. 18 books = Rs. 2000 × (126/100) = Rs. 2520

Then,the selling price of single book = Rs. 2520/18 = Rs. 140

He gives 20% discount on the marked price of a book.

That means, when the selling price is Rs. 80 then the marked price is Rs. 100.

∴When the selling price of single book is Rs. 140, the marked price = Rs. 140 × (100/80) = Rs. 175

∴The percentage increase in marked price from the cost price = (175 –100)% = 75%

Let the interest rate be r%

We know that,

S.I = PTR/100

=> (1540 x 5 x r)/100  +  (1800 x 4 x r)/100 = 1788

=> r = 178800/14900 = 12%