Dr Raju's GRE Questions Only

[vai5005]

Hi Friends please post difficult question from Dr. Raju's GRE question here.

This thread is specifically for those questions

 

Given two concentric circles, one inscribed in another. If the radius of the inner circle is 'x' & the radius of the outer circle is '(x+y)', then what is the probability that the point taken lie in the inner circle?

A. pi*x^2/(x+y)

B. x^2/(x+y)^2

C. x^2/(x^2+y^2)

D. x/(x+y)

& so on....

 

If the range of 6 consecutive positive numbers is 6.8 and of 7 consecutive numbers is 13.2. If none of these numbers in the two groups are same, then find the range of the 13 numbers?

 

my ans:

1.B

2.20

[vai5005]

Given a triangle ABC. A point 'D' divides the side AB such that a traingle ADC is formed and AD/DB=1/3. If the area of the triangle ABC is 'r', then find the area of the triangle ADC in terms of 'r'?

 

please solve this problem and above problems.

[vai5005]

6. Given a series k, k-1, k+3, k+1, k+2. Find the ratio of mean and standard deviation?

A. k+1

B. k

C. 1

D. 1/k

E. 1/(k+1)

 

5. Given set A = {1,2,3} and set B = {1,2,3,6,7,8}

If a set M exists, such that set A is a subset of set M and set M is a subset of set B & set M is not equal to set A or set B. How many such possible sets exists?

A. 4

B. 5

C. 6

D. 8

E. 9

 

guys please help.

 

i think nobody is here solving these questions:hmm::hmm:

[SuperFlanker]

A lot of these questions to me don't make any sense.

 

1st one is B

2nd one makes no sense. First, a consecutive number generally applies to integers. Rationals and reals are infinitely dense so it doesn't make sense to think of the next consecutive numbers. If one makes the assumption it is an integer, the range is high -low:

let low be x and high be x + 5, the range is then 5

 

The triangle problem seems impossible because all you know is a side.

 

The series is also impossible. There should be a square root since we are dealing with STD:

mean is k + 1

variance = (1 + 4 + 4 + 0 + 1)/5 = 10/5 = 2

 

The last question implies that B must be at least 4 elements and cannot be 6 elements. Therefore: 3C1 + 3C2

[harishr1981]

Q1. answer is B

Q2. 20 might not be the answer because there can be a diffrence between end of range 1 and start of range 2

Q3. if AB is base and is divided by D, AD=2BD, then A(DBC)=2*A(ADC)

Q4. after sorting the number mean is K+1 and deviation is 1.4, so ratio should resule in K, answer B.

Q5. answer is 6, 3c1+3c2=3+3=6

[vai5005]

harishr1981

i am not getting your explanation for question 3.

will you please explain the which property of triangle or proof your are trying to use here.

 

by the here is one more question

 

 

4. Given a series 7, 8, 13, 13, 9, 14, 15, 15, 15, 19. If another number 15 is included in the series, then which will be most affected?

A. Mean

B. Median

C. Mode

D. None

 

my answer is median

 

since in terms of % comparison

change for mean is .2/12.8 vs change in median .5/13.5

therefore my answer is median

 

please provide your comments

[jahangir27]

would you please expalin the answer B (the probability one)?

[jahangir27]

The answers is r/6

[Md. Minuddin]

The answer of Q-5 is 3C1+3C2 is correct

[Md. Minuddin]

For Jahangir27 about the answer of Q-1Here total area is Pie(x+y)^2 and area in favor is Pie(x^2). So probability will be (area in favor)/(Total area) that is (x^2)/(x+y)^2

[jahangir27]

Problem using rate, time and

 

Problem using rate, time and distance formula

 

distance formula

 

Karen can row a boat 10 kilometers per hour in still water. In a river where the current is 5 kilometers per hour, it takes her 4 hours longer to row a given distance upstream than to travel the same distance downstream. Find how long it takes her to row upstream, how long to row downstream, and how many kilometers she rows?

[Md. Minuddin]

If the distance is X then,

(X/5)-(X/15)=4 =>X=30

So,1. He row 30 km

2. It takes 6 hour to row upstream

3. It takes 2 hour to row downstream

[kappe]

@ Jahangir

can you please explain how the area of triangle is r/6

[jahangir27]

For Jahangir27 about the answer of Q-1Here total area is Pie(x+y)^2 and area in favor is Pie(x^2). So probability will be (area in favor)/(Total area) that is (x^2)/(x+y)^2

 

 

would you please expalin the Q5 for me?

 

 

thanks

[jahangir27]

You are absolutely right. I got the same answers. Thanks

[jahangir27]

Q: Given a triangle ABC. A point 'D' divides the side AB such that a traingle ADC is formed and AD/DB=1/3. If the area of the triangle ABC is 'r', then find the area of the triangle ADC in terms of 'r'?

 

It was given,

 

AD/BD= 1/3, We can write, AD/BD=AREA OF TRIANGLE ADC/AREA OF TRAINGLE BCD=1/3 (ratio formula), then we can add area of triangle ADC on the numerator and denominator and we will get

 

2 ADC/ABC= 1/3,

2 ADC/r= 1/3,

ADC= r/6

 

Am I right?

[AC2009]

Can someone please solve these 3 questions -

 

1) A man buys ‘W’kgs of dog food once in a week and ‘x’kgs of the food is given to each dog twice a day.

Col A: Number of dogs

Col B: W/7x

 

2) Given a sequence a1, a2........ an. If a1 = 25 & in the sequence if every number is '-2' times the preceding number, then

Col A: a100

Col B: -10,000

 

3) Given that the time taken by a train to travel a distance ’d’ is ‘h’hrs and the next day the train travels the same distance but reaches 15 min early. What is the average speed on that day?

 

 

thanks!

[vai5005]

1 ans is B

 

as W = 2x * 7 * no of dogs.

 

2 ans is B

 

since in general we get an = 25 * (-2)^(n-1)

put n = 100

 

3. please provide explaination i could not solve it.

[smbabu]

area of the inner circle is pi x^2 and that of outer is pi(x+y)^2

the probability = possible outcome/total outcome

[smbabu]

therefore, probability=pi x^2/{pi (x+y)^2}

= x^2/(x+y)^2

the answer is B

[Kronos]

1) If the food was given to the dogs once per day it would be

Number of dogs = Total Weekly Food/Days of the Week*Food per dog = W/7x

But as the food is given to them twice per week it is W/7*2x

Therefore, Column B is bigger because W/7x > W7*2x

2) Colum A

If A1 = 25 A2 = 23, A3 = 21 etc.

No way that reaches -10000 as 99*-2 =-198

Therefore A

3) Distance = Ratio * Time

Distance/Time = Ratio

Distance/Time-15 = Ratio

Remember to do it in minutes, not in hours and maybe convert afterwards

[smbabu]

area of the inner circle is pi x^2 and that of outer is pi(x+y)^2

the probability = possible outcome/total outcome

= pi x^2/{pi (x+y)^2}

= x^2/(x+y)^2

 

the answer is B

[smbabu]

area of the inner circle is pi x^2 and that of outer is pi(x+y)^2

the probability = possible outcome/total outcome

= pi x^2/{pi (x+y)^2}

= x^2/(x+y)^2

 

the answer is B

[Kronos]

Q: Given a triangle ABC. A point 'D' divides the side AB such that a traingle ADC is formed and AD/DB=1/3. If the area of the triangle ABC is 'r', then find the area of the triangle ADC in terms of 'r'?

 

It was given,

 

AD/BD= 1/3, We can write, AD/BD=AREA OF TRIANGLE ADC/AREA OF TRAINGLE BCD=1/3 (ratio formula), then we can add area of triangle ADC on the numerator and denominator and we will get

 

2 ADC/ABC= 1/3,

2 ADC/r= 1/3,

ADC= r/6

 

Am I right?

 

If we take AD as the base of the first triangle and the ratio is 1:3 it tells us that, as AD includes BD, AD = 4 BD. As they both have C in common their height is the same.

1/2*AD*h=r

Area of Smaller Triangle = 1/2*1/4AD*h = 1/8*AD*h = 1/4(1/2*AD*h) = 1/4r =r/4

[AC2009]

thanks kronos ....

 

Q1) I too got your answer however the answer posted was C ( both are equal) so wanted to make sure.

 

Q2) shouldn't the series be like 25, -50, 100, -200 ..... and so on?

 

Q3) if i have to calculate the average speed for THAT day, is it d/(h-15/60). please tell me if this is right...