Official Quant thread for CAT 2013

MBA CAT 2024
26908
@bodhi_vriksha said:
No ..wrong answer but would like to know your approach . What's your approach?Team BV--Pratik Gauri
Haan realised a little after posting that I had made a cancelling mistake (not sure about concept mistake) by what I did should have got 750ish....

1st case A running 1000 B running 960 gap 19 s for A
2nd case A running 960 B running 1000 gap 30 s for A

I converted the second case to A running 1000, B running 1000*25/24 i.e 1041.66 m and time gap will be 30 * 25/24 = 31.25 for A. (Idea being to remove A from the story)

So B runs the extra 1041.66 - 960 = 81.66 in 31.25 - 19 = 12.25 s so he will run 5000 in 5000*12.25 /81.66 = 5000 * 49/4 * 3/245 = 750 s?

regards
scrabbler
26909
@bodhi_vriksha said:
@scrabbler share your oral approach Team BV--Pratik Gauri
Oral = still requiring heavy calculations 😃 I just like doing mental calcs 😁 :o

Edit: But still mistakes do happen (as ATDH's signature says!)

regards
scrabbler
26910
@scrabbler Sexy!!

@bodhi_vriksha Sir, Calculations to hai..no use of posting because it is not a good approach! :/
26911
@bodhi_vriksha said:
Il check once i reach home at 8 dont worry One ques from my side : In a km race, if A gives a start of 40m to B, A wins by 19s. If A gives B a 30 sec start , B wins by 40 m. Find time taken by B to run 5000m .Do post your approach . Let's see who solves in the shortest way Team BV--Pratik Gauri
750 secs is it sir?
26912
@fireatwill said:
1! + (1!+2!) + (1!+2!+3!)..... + (1!+....+22!) = ?
@scrabbler Karo..

P.S. Orally
26913
@ScareCrow28 said:
@scrabbler Karo..P.S. Orally
Done. It is equal to:

22*1! + 21*2! + 20*3! =.... +2 *21! + 22!

or

Summation from 1 to 22 {x! * (23-x)}

regards
scrabbler
26914
@scrabbler said:
Done. It is equal to:22*1! + 21*2! + 20*3! =.... +2 *21! + 22!orSummation from 1 to 22 {x! * (23-x)}regardsscrabbler
:mg:
26915
@bodhi_vriksha said:
Il check once i reach home at 8 dont worry One ques from my side : In a km race, if A gives a start of 40m to B, A wins by 19s. If A gives B a 30 sec start , B wins by 40 m. Find time taken by B to run 5000m .Do post your approach . Let's see who solves in the shortest way Team BV--Pratik Gauri
method
(960-19b)/b = 1000/a
(1000-30b)/b = 960/a
divide both the eqs
1000^2 - 960^2 = (30*1000- 19*960)b
speed b= 6.666

so time taken to run 5000 = 5000/6.66 = 750.75
26916
@scrabbler i did not understand the last step

" summation from 1 to 22{x!*(23-x)} ""
26917
@fireatwill said:
@scrabbler i did not understand the last step" summation from 1 to 22{x!*(23-x)} ""
Another way of stating the above thing....summation from 1 to 22 implies woh jo sigma sign use karte they....with 1 below and 22 above...

regards
scrabbler
26918
@psk.becks said:
@silentstriker said:OA KYA HAI.....
@psk.becks : OA is A and D respectively.
26919
@scrabbler said:
Another way of stating the above thing....summation from 1 to 22 implies woh jo sigma sign use karte they....with 1 below and 22 above...regardsscrabbler
I was expecting a number, myself bashing my head for properties of prime number factorials if any .
26920
(skip if it is repeated )
and




26921
@albiesriram said:
I was expecting a number, myself bashing my head for properties of prime number factorials if any .
1234002202313888987200

Courtesy: Wolframalpha

http://www.wolframalpha.com/input/?i=sum%28+x!*%2823-x%29+%29+for+x+from+1+to+22

No way we were expected to calculate that? 😲 Especially orally @ScareCrow28

regards
scrabbler
26922
@scrabbler said:
1234002202313888987200

Even Scientific calculator wont be suffice.. NO patterns found even if we insert '-' between

26923
@albiesriram said:
(skip if it is repeated )and
is it 448?
26924
@Subhashdec2 said:
is it 448?
Yup Post the approach please..
26925
@albiesriram said:
Yup Post the approach please..
see 7 will always be added
no of sets with 7 would be =2^6=64
64*7=448

no of sets where 6 would be added will be sets containing 6 but not 7=2^5=32
sets where 6 would be subtracted sets containing 6 and 7 both=2^5=32
32-32=0

similar would happen with all other nos
every no would be added and subtracted same no of times

hence 7*64=448
26926
@albiesriram said:
(skip if it is repeated )and
1st one already done!
2nd one same as @Subhashdec2 448
26927


and