Official Quant thread for CAT 2013

MBA CAT 2024
11081
@nole said:
@YouMadFellow yeah sorry 11 minute 30 seconds.If hears second bullet sound at 11 minute 30 seconds doesn't that mean he took 30 seconds to cover 330t-330(t-12) i.e 3960 metres ?i think i was wrong he took 11 minutes 30 seconds to cover that distance ?because thinking like that only i formed the equation 3960=v*0.5
See, think the sound as a "car" approaching you.

Now, let's think of that moment when you hear the first bullet. Pause the moment, take a look around, and relax :D

Now, that you have got hold of the situation, look straight ahead. What do see is the distance between you and the second bullet's sound ? 3960 meters, right.

Fine, now that this is clear. Let's see what will happen when you "unpause" the moment.
You will start moving towards the second bullet sound, and the bullet sound will also move towards you.

So, both of you will meet after 11 minutes 30 seconds = 690 seconds.

Within this time, what is the distance that the bullet sound traveled ? Speed * Time = 330 * (11.5) = 3795.

But, what about the rest (3960 - 3795 = 165), who traveled that ? You. It's all you.
So, what is your speed? Distance/ Time = 165/(11.5) = 330/23

PS: Sorry for the long post. I love explaining myself a lot , that's why I am not very good with girls :splat:
11082
@YouMadFellow haha thanks a lot man:) I am very weak in maths so such silly questions and consequently gal goes out of the equation for me too 😛 thanks for the hillarious explanation 😃 For me maths is fun now all thanks to pg and guys like u.thanks will not suffice bt that's all i have for now what u guys explain in say 20 seconds,it takes 10 minutes for me to solve hahah so lots of catching to do
thanks for the explaining.i understood,not lying :)
11083
@nole said:
@YouMadFellowvinay fires two bullets from the same place at an interval of 12 minutes but raju sitting in a train approaching the place hears the second report 11 minutes 30 seconds after the first.What is the approximate speed of the train ?(is sound travels at the speed of 330 metres per second)I am sorry for again troubling u for the same question i absolutely got the left hand side i.e 3960 as a distance.now on the right hand side why it is (330+v)*11.5 and not v*0.5 ?? I know this is relative velocity question,but after i have got the distance travelled by train between the first and second sound.now to travel this distance(3960) train required 30 seconds,coz he heard the second sound 30 seconds after the first. the distance 3960 was travelled by train alone right,so why are we adding velocities?why m i not doing just 3960=v*0.5 ? I said that i understood that day but when i tried again,was not able to convince myself
330/x = 720/30
speed = 13.75 m/sec
11084
@rahulnema said:
330/x = 720/30speed = 13.75 m/sec
I think the answer is 330/23 = 14.35 m/s
11085
@YouMadFellow said:
I think the answer is 330/23 = 14.35 m/s
no, it will be 13.75 m/s... 330/24 (720/30=24) ..getting ??
11086
@rahulnema said:
no, it will be 13.75 m/s... 330/24 (720/30=24) ..getting ??
Can you explain why ? 😃

I had already solved it and the one who posted the question acknowledged that the answer is 330/23 m/s
11087
@sujamait said:
root x + y = 7x + root y = 11find x,y...straight from google doodle...
9 and 4 satisfying!
11088
Check Level of Maths in your Blood:

If x^x^3 = 3, then find the value of x.

(Do not use wolfram)

www.facebook.com/MathsByAmiya

11089
@YouMadFellow said:
See, think the sound as a "car" approaching you.Now, let's think of that moment when you hear the first bullet. Pause the moment, take a look around, and relax
PS: Sorry for the long post. I love explaining myself a lot , that's why I am not very good with girls
Love the way of explanation 😃 Keep it going :)
11090
@floamiya said:
Check Level of Maths in your Blood:If x^x^3 = 3, then find the value of x.(Do not use wolfram)www.facebook.com/MathsByAmiya
x^3=k
=> x=k^(1/3)
=> x^k=3
=> {k^(1/3)}^k3=3
=> {k^k}^(1/3)=3

==> k=3

==> x=k^(1/3)=3^(1/3)
11091
@vijay_chandola said:
x^3=k=> x=k^(1/3) iske bad how come this=> x^k=3=> {k^(1/3)}^k3=3=> {k^k}^(1/3)=3==> k=3==> x=k^(1/3)=3^(1/3)
11092
@ayushnasa said:
Nevermind :splat: Question hi tha wo to :splat:
11093
@ayushnasa said:
x^(x^3)=3
=> x^k=3 (as we have x^3=k)

This one is really confusing :mg:
11094
@YouMadFellow said:
Can you explain why ? I had already solved it and the one who posted the question acknowledged that the answer is 330/23 m/s
ok. got you.. you are correct..

simply, S inversely proportional to T..

S1/S2 = T2/T1 .. also the ratio of time taken by bullet and train is 690/30 (to meet)

330/x = 690/30
so, x = 14.35 m/sec ..hope i am making my point clear, was messing up in time part earlier..

thanks :)
11095
@rahulnema said:
ok. got you.. you are correct..simply, S inversely proportional to T..S1/S2 = T2/T1 .. also the ratio of time taken by bullet and train is 690/30 (to meet)330/x = 690/30so, x = 14.35 m/sec ..hope i am making my point clear, was messing up in time part earlier..thanks
Yes, exactly 😃 .. :thumbsup:

You took the complete 12 minutes instead of 11.5 minutes :)
11096
@YouMadFellow said:
Yes, exactly .. You took the complete 12 minutes instead of 11.5 minutes
actually, this is valid when the train is moving far from the object.. :)
11097

A garrison of 600 men had provisions for 28 days.After 4 days, a reinforcement of 200 men arrived.
The food will now last for how many days???

PLease give a detailed solution.
Any help to solve such ratio problems ?????????
11098
@12sahil12 said:
A garrison of 600 men had provisions for 28 days.After 4 days, a reinforcement of 200 men arrived.The food will now last for how many days???PLease give a detailed solution.Any help to solve such ratio problems ?????????
18 days?
11099
Find The Mines : There are how many mines in the figure and at which place.

Digits are indicating the number of mines in adjacent squares

M B A - Maths By Amiya



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11100
@12sahil12 said:
A garrison of 600 men had provisions for 28 days.After 4 days, a reinforcement of 200 men arrived.The food will now last for how many days???PLease give a detailed solution.Any help to solve such ratio problems ?????????
let x be total provisions

x=600*28

after 4 days ==> 600*28-600*4=600*24

total men=800

==> 800*d=600*24
==> d= 18