Official Quant thread for CAT 2013

A,B,C .......A is 40 % more efficient than B and B is 20% more efficient than C . if A starts the work and did for 10 days after B did for 15 days how long will it take C to complete the balance work
@rkshtsurana said:
aadha hga na uska
ha ya..made a mess again.

its 4.25
In a right angled triangle ABC, angle B is right angle, side AB is half of the hypotenuse. AE is parallel to median BD and CE is parallel to BA. What is the ratio of length of BC to that of EC?
@rkshtsurana said:
A fair coin is tossed n times. What is the probability that no two consecutive heads appear?
Probability = f(n)/2 ż
where f(n) is nth term of fibonacci series such that f(1) = 2 and f(2) = 3
@soumitrabengeri said:
The lengths of the hour hand and the minute hand of a clock are 3.5 cm and 5.25 cm respectively. If the hour hand covers an area of 7.7 cm2, then find the approximate area (in cm2) covered by the minute hand during the same time period.(a) 17 (b) 158 (c) 260 (d) 208Please explain with approach
207.9=208?
@chillfactor said:
Probability = f(n)/2 żwhere f(n) is nth term of fibonacci series such that f(1) = 2 and f(2) = 3
saar _/\_
U can never be wrong
@arumugadas said:
A,B,C .......A is 40 % more efficient than B and B is 20% more efficient than C . if A starts the work and did for 10 days after B did for 15 days how long will it take C to complete the balance work
i think some data is missing
@arumugadas said:
A,B,C .......A is 40 % more efficient than B and B is 20% more efficient than C . if A starts the work and did for 10 days after B did for 15 days how long will it take C to complete the balance work
7.2 days?????
@arumugadas 18.75 days??
@maddy2807 said:
@soumitrabengeriAGAIN...Sparsh is the brother of the father of Paresh's sister's father's mother. How is Paresh's father's mother is related to Sparsh's son?
Cousin brother?
@rkshtsurana said:
saar _/\_
U can never be wrong
how to find that nth Term and whats the OA
@pratyush9811 said:
In a right angled triangle ABC, angle B is right angle, side AB is half of the hypotenuse. AE is parallel to median BD and CE is parallel to BA. What is the ratio of length of BC to that of EC?
rt3 : 4 ?
@pratyush9811 said:
In a right angled triangle ABC, angle B is right angle, side AB is half of the hypotenuse. AE is parallel to median BD and CE is parallel to BA. What is the ratio of length of BC to that of EC?

edit:
BC=rt(3)x/2where x=AB
EC=2x

rt(3):4


@techsurge said:
how to find that nth Term and whats the OA
detailed solution from source
Let f(n) be the number of sequences of heads and tails, of length n, in which two consecutive heads do not appear.
The total number of possible sequences from n coin tosses is 2^n.
So the probability that no two consecutive heads occur in n coin tosses is f(n) / 2^n.
By enumeration, f(1) = 2, since we have {H, T}, and f(2) = 3, from {HT, TH, TT}.
We then derive a recurrence relation for f(n), as follows.
A sequence of n > 2 coin tosses has no consecutive heads if, and only if:
It begins with a tail, and is followed by n−1 tosses with no consecutive heads; or
It begins with a head, then a tail, and is followed by n−2 tosses with no consecutive heads.
These two possibilities are mutually exclusive, so we have f(n) = f(n−1) + f(n−2).
This is simply the Fibonacci sequence, shifted forward by two terms.
The Fibonacci sequence is defined by the recurrence equation F1 = 1,F2 = 1,Fk = Fk−1 + Fk−2,for k > 2.
So F3 = 2 and F4 = 3, and therefore f(n) = Fn+2.
A closed form formula for the Fibonacci sequence is Fn = (Phin − phin) /,
where Phi = (1 + rt5)/2 and phi = (1 − rt5)/2 are the roots of the quadratic equation x2 − x − 1 = 0.
Therefore the probability that no two consecutive heads appear in n tosses of a coin is Fn+2 / 2n = (Phi^n+2 − phi^n+2) / 2^n. rt5


@19rsb said:
7.2 days?????
method pls

@pratyush9811 said:
@arumugadas 18.75 days??
nope

@pratyush9811 said:
In a right angled triangle ABC, angle B is right angle, side AB is half of the hypotenuse. AE is parallel to median BD and CE is parallel to BA. What is the ratio of length of BC to that of EC?
rt3:4?
@pratyush9811 said:
In a right angled triangle ABC, angle B is right angle, side AB is half of the hypotenuse. AE is parallel to median BD and CE is parallel to BA. What is the ratio of length of BC to that of EC?
rt3/2????
@techsurge said:
how to find that nth Term and whats the OA
I don't think you will be asked for some variable 'n'. If this question appears then you will be given some value of n, say, 10

then f(1) = 2, f(2) = 3
In fibonacci sequence f(n) = f(n - 1) + f(n - 2)
so, f(3) = 5, f(4) = 8, f(5) = 13, f(6) = 21, f(7) = 34, f(8) = 55, f(90 = 89 and f(10) = 144

So, probability = 144/1024 = 9/64
@pratyush9811 ratio:: rt(3):2 ?