31
Q:

# A thief is noticed by a policeman from a distance of 200 m. The thief starts running and the policeman chases him. The thief and the policeman run at the rate of 10 km and 11 km per hour respectively. What is the distance between them after 6 minutes?

 A) 100 m B) 150 m C) 190 m D) 200 m

Explanation:

Relative speed of the thief and policeman  =  (11 – 10) km/hr = 1 km/hr

Distance covered in 6 minutes  = ${\color{Blue}&space;\left&space;(&space;\frac{1}{60}\times&space;6&space;\right&space;)}$ km   = ${\color{Blue}&space;\frac{1}{10}}$ km = 100 m

${\color{Blue}&space;\therefore&space;}$ Distance between the thief and policeman = (200 – 100) m = 100 m.

Q:

Three friends Rudra, Siva and Anvesh start to run around a circular stadium. They complete a revolution in 24, 36 and 30 seconds respectively. After how many minutes will they meet at the starting point ?

 A) 60 B) 120 C) 360 D) 6

Explanation:

For this we have to find the LCM of 24, 36 and 30

LCM of 24, 36 and 30 = 360 sec

360/60 min = 6 minutes.

8 120
Q:

Amith can row a boat d km upstream and the same distance downstream in 5 hours 15 minutes. Also, he can row the boat 2d km upstream in 7 hours. How long will it take to row the same distance 2d km downstream for Amith ?

 A) 4 hrs 10 min B) 3 hrs 15 min C) 3 hrs 30 min D) 4 hrs 1 min

Explanation:

Let the speed of boat and stream be x and y kmph respectively.

According to question

d/x+y + d/x-y = 5h 15m or 21/4 hrs ......(i)

and 2d/x-y = 7...... (ii)

From eq. (i) and (ii)

2d/x+y = 7/2

Hence, Amith will take to row 2d km distance downstream in 7/2 hrs

= 3.5 hrs

= 3 hrs 30 min.

5 148
Q:

Kamal consistently runs 240 meters a day and on Saturday he runs for 400 meters. How many kilometers will he have to run in four weeks ?

 A) 5.75 kms B) 7.36 kms C) 8.2 kms D) 6.98 kms

Explanation:

Total running distance in four weeks = (24 x 240) + (4 x 400)

= 5760 + 1600

= 7360 meters

= 7360/1000

=> 7.36 kms

4 177
Q:

K and L starts walking towards each other at 4 pm at speed of 3 km/hr and 4 km/hr respectively. They were initially 17.5 km apart. At what time do they meet ?

 A) 6:00 am B) 6:30 pm C) 5:45 am D) 5:52 pm

Explanation:

Suppose they meet after 'h' hours

Then

3h + 4h = 17.5

7h = 17.5

h = 2.5 hours

So they meet at => 4 + 2.5 = 6:30 pm

9 271
Q:

P, Q and R start simultaneously from A to B. P reaches B, turns back and meet Q at a distance of 11 km from B. Q reached B, turns back and meet R at a distance of 9 km from B. If the ratio of the speeds of P and R is 3:2, what is the distance between A and B ?

 A) 99 B) 100 C) 89 D) 1

Explanation:

Let, Distance between A and B = d

Distance travelled by P while it meets Q = d + 11

Distance travelled by Q while it meets P = d – 11

Distance travelled by Q while it meets R = d + 9

Distance travelled by R while it meets Q = d – 9

Here the ratio of speeds of P & Q => SP : SQ = d + 11 : d – 11

The ratio of speeds of Q & R => SQ : SR = d + 9 : d – 9

But given Ratio of speeds of P & R => P : R = 3 : 2

$\inline \fn_jvn \frac{SP}{SR} = \frac{SP}{SQ}x\frac{SQ}{SR} = \frac{(d+11)(d+9)}{(d-11)(d-9)}$

=> $\inline \fn_jvn \frac{(d+11)(d+9)}{(d-11)(d-9)}=\frac{3}{2}$

=>  d = 1, 99

=> d = 99 satisfies.

Therefore, Distance between A and B = 99