GMAT Problem Solving Discussions

MBA
3221
It took Ellen 6 hours to ride her bike a total distance of 120 miles.
For the first part of the trip, her speed was constantly 25 miles per hour.
For the second part of her trip, her speed was constantly 15 miles per hour. For how many miles did Ellen travel at 25 miles per hour?

(A) 60
(B) 62.5
(C) 66 2/3
(D) 75
(E) 80


@ 15 mph, in 3 hrs -> 45miles
@ 25 mph, in (6-3)hrs ->75 miles

45+75=120..

IMO - D
3222
It took Ellen 6 hours to ride her bike a total distance of 120 miles.
For the first part of the trip, her speed was constantly 25 miles per hour.
For the second part of her trip, her speed was constantly 15 miles per hour. For how many miles did Ellen travel at 25 miles per hour?

(A) 60
(B) 62.5
(C) 66 2/3
(D) 75
(E) 80


IMO = D

I II

Why not try options!!!
easy to put are 60, 75 and 80...

i took 75 first (tempted by the fact that it is divisible by 25), that meant 75/25 = 3 hrs in part 1 and (120-75)/15 = 3 Hours in second part...

So total 6 hours... Hence luckily GOT the answer in the first go.
3223

Solve the below one:

1.If y 3 and is a prime integer greater than 2, which of the following must be true?
. x = y
. y = 1
. x and y are prime integers.
(A) None
(B) only
(C) only
(D) only
(E) and


2.A certain basketball team that has played of its games has a record of 17 wins and 3 losses. What is the greatest number of the remaining games that the team can lose and still win at least of all of its games?
(A) 7
(B) 6
(C) 5
(D) 4
(E) 3

3224

solve the below one

A certain number k has 8 factors. Which among the following cannot be the possible number of factors of k3?
OPTIONS

1)22
2)27
3)40
4)64
5)None of these

3225
It took Ellen 6 hours to ride her bike a total distance of 120 miles.
For the first part of the trip, her speed was constantly 25 miles per hour.
For the second part of her trip, her speed was constantly 15 miles per hour. For how many miles did Ellen travel at 25 miles per hour?

(A) 60
(B) 62.5
(C) 66 2/3
(D) 75
(E) 80


The ratio of speeds in which Ellen traveled is 5:3, hence the distance that she traveled also has to be in the same ratio. Now divide 120 into that ratio. Result is 75 and 45 miles.
3226

Thats even faster!

3227
tiknA_atpuG Says
The ratio of speeds in which Ellen traveled is 5:3, hence the distance that she traveled also has to be in the same ratio. Now divide 120 into that ratio. Result is 75 and 45 miles.


Speed is directly proportional to distance only when the time is constant.I guess in the above case the travel timing in both the parts are same so its the ratio of speeds can give you the distances.
3228

A simple question that is confused by most.. including me...
In How many ways can 5 rings be worn on the 4 fingers of the right hand. .
a) 5C4 b) 5P4 c)5^4 d)4^5...

plz answer with explanation..

3229
solve the below one

A certain number k has 8 factors. Which among the following cannot be the possible number of factors of k3?
OPTIONS

1) 22
2) 27
3) 40
4) 64
5) None of these


Deepak



I think there are 2 answers to this question .

As we know for calculating the no. of factors of a no. we multiply the (powers
Of prime factors+1).

Choice 1 is 22. which can be possible to get if we assume K= X(power)7
Choice 2 is 27. Not possible, to get 27 we need to have 9*3 which is not possible by taking any no. of prime factors of K.
Choice 3 is 40. Not possible, to get 40 we require 8*5, we cannot get 5 as multiplying factor.
Choice 4 is 64: which is possible if we consider K= XYZ..

Please correct me if I am wrong..
3230
Deepak



I think there are 2 answers to this question .

As we know for calculating the no. of factors of a no. we multiply the (powers
Of prime factors+1).

Choice 1 is 22. which can be possible to get if we assume K= X(power)7
Choice 2 is 27. Not possible, to get 27 we need to have 9*3 which is not possible by taking any no. of prime factors of K.
Choice 3 is 40. Not possible, to get 40 we require 8*5, we cannot get 5 as multiplying factor.
Choice 4 is 64: which is possible if we consider K= XYZ..

Please correct me if I am wrong..




40 can also be written as 10*4.Think now
3231
A simple question that is confused by most.. including me...
In How many ways can 5 rings be worn on the 4 fingers of the right hand. .
a) 5C4 b) 5P4 c)5^4 d)4^5...

plz answer with explanation..


IMO D
1 ring can be worn in 4 ways
similarly ring 2 also can be worn in 4 ways...and so on.. clearly total no of ways 5 rings can be worn in 4 fingers are 4*4*4*4*4 ie 4^5
3232

A certain manufacturer of cake , muffin and bread mixes has 100 buyers, of whom 50 purchases cake mix , 40 purchases muffin mix and 20 purchases both cake mix & muffin mix.If a buyer is to be selected at random from the 100 buyers, what is the probability that the buyer selected will be one who purchases neither cake mix nor muffin mix?
a) 1/10 b) 3/10 c) 1/2 d) 7/10 e) 9/10

3233
A certain manufacturer of cake , muffin and bread mixes has 100 buyers, of whom 50 purchases cake mix , 40 purchases muffin mix and 20 purchases both cake mix & muffin mix.If a buyer is to be selected at random from the 100 buyers, what is the probability that the buyer selected will be one who purchases neither cake mix nor muffin mix?
a) 1/10 b) 3/10 c) 1/2 d) 7/10 e) 9/10

is it B) 3/10 ??
3234
A simple question that is confused by most.. including me...
In How many ways can 5 rings be worn on the 4 fingers of the right hand. .
a) 5C4 b) 5P4 c)5^4 d)4^5...

plz answer with explanation..


-->
for 1st finger, one can select from 5 rings
for 2nd finger, one can select from 4 rings
for 3rd finger, one can select from 3 rings
for 4th finger, one can select from 2 rings

Hence, Ans- > 5*4*3*2 ~ 5P4

IMO - B

OA pls...
3235
Solve the below one:

1.If y 3 and is a prime integer greater than 2, which of the following must be true?
. x = y
. y = 1
. x and y are prime integers.
(A) None
(B) only
(C) only
(D) only
(E) and


2.A certain basketball team that has played of its games has a record of 17 wins and 3 losses. What is the greatest number of the remaining games that the team can lose and still win at least of all of its games?
(A) 7
(B) 6
(C) 5
(D) 4
(E) 3


@deepak, can u pls check the above ques.. i guess there are a few typos, coz the ques don make sense...

Thanks..
3236
It took Ellen 6 hours to ride her bike a total distance of 120 miles.
For the first part of the trip, her speed was constantly 25 miles per hour.
For the second part of her trip, her speed was constantly 15 miles per hour. For how many miles did Ellen travel at 25 miles per hour?

(A) 60
(B) 62.5
(C) 66 2/3
(D) 75
(E) 80

distance travelled in part 1=x
distance travelled in part 2=y
x+y=120

x/25+y/15=6

solving
x=75
3237
A certain manufacturer of cake , muffin and bread mixes has 100 buyers, of whom 50 purchases cake mix , 40 purchases muffin mix and 20 purchases both cake mix & muffin mix.If a buyer is to be selected at random from the 100 buyers, what is the probability that the buyer selected will be one who purchases neither cake mix nor muffin mix?
a) 1/10 b) 3/10 c) 1/2 d) 7/10 e) 9/10


I'm getting the ans as 3/10
3238
A certain manufacturer of cake , muffin and bread mixes has 100 buyers, of whom 50 purchases cake mix , 40 purchases muffin mix and 20 purchases both cake mix & muffin mix.If a buyer is to be selected at random from the 100 buyers, what is the probability that the buyer selected will be one who purchases neither cake mix nor muffin mix?
a) 1/10 b) 3/10 c) 1/2 d) 7/10 e) 9/10


venn diagram is the best to solve such questions.

no buyers of cake and mix=100-(30+20+20)=30

p(e)=30/100=3/10
3239

posting the qs after the modifications

1.If y 3 and x is a prime integer greater than 2, which of the following must be true?
i) x = y
ii) y = 1
iii). x and y are prime integers.
(A) None
(B) i only
(C) ii only
(D) iii only
(E) i and iii


2.A certain basketball team that has played 2/3 of its games has a record of 17 wins and 3 losses. What is the greatest number of the remaining games that the team can lose and still win at least of all of its games?
(A) 7
(B) 6
(C) 5
(D) 4
(E) 3

3240
posting the qs after the modifications

1.If y 3 and x is a prime integer greater than 2, which of the following must be true?
i) x = y
ii) y = 1
iii). x and y are prime integers.
(A) None
(B) i only
(C) ii only
(D) iii only
(E) i and iii


2.A certain basketball team that has played 2/3 of its games has a record of 17 wins and 3 losses. What is the greatest number of the remaining games that the team can lose and still win at least of all of its games?
(A) 7
(B) 6
(C) 5
(D) 4
(E) 3

how can it win all of it's games if it's already lost 3?? :shocked:


1.
y can be 1,2,4,5.....
x can be 3,5,7....
No way of confirming the 3 options..
IMO- A None