GMAT Problem Solving Discussions

MBA
2821
Determine in what ratio must water be mixed with milk so as to gain 30% by selling this mixture at cost price?
a.3:10
b.1:3
c.3:5
d.2:3
need help..

a-3/10 should be the answer !!!

Dude.. This is adulteration problem which is Out of Syllabus for GMAT.

You should post this in CAT problem solving discussions.
2822
Nice one!!

IMO - 'B'

wats the OA??
I can explain if the answer's right!

thats correct... B is the answer...

waiting for your analysis...
2823

Hey pj02...need expln.. i donno d ans.. just found in a gmat quiz site..

2824
This year Henry will save a certain amount of his income, and he will spend the rest. Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend. In terms of r, what fraction of his income should Henry save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?
A) 1 / R+2
B) 1/(2R+2)
C) 1/(3R+2)
D) 1/(R+3)
E) 1/(2R+3)

This Year
income -I

saving- x

spent- I-x

Next Year

income-0

saving-x

Spent-1+r
---------------------------------------

We have to find-->x/I

According to given condition:-

x(1+r)=(I-x)/2

=>x/I=1/(2R+3)

Please post the OA.
2825
This year Henry will save a certain amount of his income, and he will spend the rest. Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend. In terms of r, what fraction of his income should Henry save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?
A) 1 / R+2
B) 1/(2R+2)
C) 1/(3R+2)
D) 1/(R+3)
E) 1/(2R+3)

hi,
i am getting E) 1/(2R+3) as the answer...
please confirm...
2826
This year Henry will save a certain amount of his income, and he will spend the rest. Next year Henry will have no income, but for each dollar that he saves this year, he will have 1 + r dollars available to spend. In terms of r, what fraction of his income should Henry save this year so that next year the amount he was available to spend will be equal to half the amount that he spends this year?
A) 1 / R+2
B) 1/(2R+2)
C) 1/(3R+2)
D) 1/(R+3)
E) 1/(2R+3)



OA is E)...thanks to all who attempted
2827
Determine in what ratio must water be mixed with milk so as to gain 30% by selling this mixture at cost price?
a.3:10
b.1:3
c.3:5
d.2:3
need help..

sdt83 Says
Hey pj02...need expln.. i donno d ans.. just found in a gmat quiz site..

You can find answer in 2 ways...
1 using regular method of alligation.
2 shortcut method

I will solve this using shortcut method:

Formula:

% Profit=Qa/Qo * 100

where,

Qa= Quantity of Adulterent
Qo=Quantity of Original.

So, For our problem :

30=Qa/Qb*100
So, Qa/Qb=3/10

So answer is 3/10.
2828
Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day. If r percent of the stores revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper A, which of the following expresses r in terms of p?

A. 100p / (125 p)
B. 150p / (250 p)
C. 300p / (375 p)
D. 400p / (500 p)
E. 500p / (625 p)
2829
Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day. If r percent of the stores revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper A, which of the following expresses r in terms of p?

A. 100p / (125 p)
B. 150p / (250 p)
C. 300p / (375 p)
D. 400p / (500 p)
E. 500p / (625 p)




Total no.of copies sold = Copies of A + Copies of B------ (1)
Total revenues = Revenue of A + Revenue of B --------(2)

Copies sold = a+b
Revenues(m) = 1*a + 1.25*b

So , a/(a+b) *100 = p

a/(a+1.25b) = r

From the options only option 4 correctly represents r interms of p.So I will go with option 4
2830

D should be the ans.

Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day. If r percent of the stores revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper A, which of the following expresses r in terms of p?
A. 100p / (125 p)
B. 150p / (250 p)
C. 300p / (375 p)
D. 400p / (500 p)
E. 500p / (625 p)
2831
Last Sunday a certain store sold copies of Newspaper A for $1.00 each and copies of Newspaper B for $1.25 each, and the store sold no other newspapers that day. If r percent of the stores revenues from newspaper sales was from Newspaper A and if p percent of the newspapers that the store sold were copies of newspaper A, which of the following expresses r in terms of p?
A. 100p / (125 p)
B. 150p / (250 p)
C. 300p / (375 p)
D. 400p / (500 p)
E. 500p / (625 p)


Ans is D...

I made the equations and tried to solve it....and then later tried to do with answer matching...i guess thats the best approach....got this a test paper...
2832

solve this

Q3:
Each participant in a certain study was assigned a sequence of 3 different letters from the
set {A, B, C, D, E, F, G, H}. If no sequence was assigned to more than one participant
and if 36 of the possible sequences were not assigned, what was the number of
participants in the study? (Note, for example, that the sequence A, B, C is different from
the sequence C, B, A.)
A. 20
B. 92
C. 300
D. 372
E. 476

2833

At a certain food stand, the price of each apple is 40 and the price of each orange is
60. Mary selects a total of 10 apples and oranges from the food stand, and the average
(arithmetic mean) price of the 10 pieces of fruit is 56. How many oranges must Mary
put back so that the average price of the pieces of fruit that she keeps is 52?
A. 1
B. 2
C. 3
D. 4
E. 5

2834
At a certain food stand, the price of each apple is 40 and the price of each orange is
60. Mary selects a total of 10 apples and oranges from the food stand, and the average
(arithmetic mean) price of the 10 pieces of fruit is 56. How many oranges must Mary
put back so that the average price of the pieces of fruit that she keeps is 52?
A. 1
B. 2
C. 3
D. 4
E. 5


I would have marked E.
Wts the OA
I'll explain it if this answer is correct
2835

C 300 ?

its a simple permutation problem: (8P3 - 36) should be the ans.

solve this

Q3:
Each participant in a certain study was assigned a sequence of 3 different letters from the
set {A, B, C, D, E, F, G, H}. If no sequence was assigned to more than one participant
and if 36 of the possible sequences were not assigned, what was the number of
participants in the study? (Note, for example, that the sequence A, B, C is different from
the sequence C, B, A.)
A. 20
B. 92
C. 300
D. 372
E. 476
2836

E. 5

Dont have a good solution. I solved using orthodox approach. Waiting for some better ones.

At a certain food stand, the price of each apple is 40 and the price of each orange is
60. Mary selects a total of 10 apples and oranges from the food stand, and the average
(arithmetic mean) price of the 10 pieces of fruit is 56. How many oranges must Mary
put back so that the average price of the pieces of fruit that she keeps is 52?
A. 1
B. 2
C. 3
D. 4
E. 5
2837
At a certain food stand, the price of each apple is 40 and the price of each orange is
60. Mary selects a total of 10 apples and oranges from the food stand, and the average
(arithmetic mean) price of the 10 pieces of fruit is 56. How many oranges must Mary
put back so that the average price of the pieces of fruit that she keeps is 52?
A. 1
B. 2
C. 3
D. 4
E. 5

Answer: E

Conventional Method:

A+O = 10
40(A) + 60(O) = 560

Solving gives, A=2, O=8

Let R be remaining oranges.
So,
60(R) + 40(2) = 52 (R+2)

Solving we get R = 3, so Mary needs to give back 5, Answer : E

Fastest Method:
Think about it for a second. Contribution of Apples remains constant as the number did not change.
Before returning X number of oranges, the average was 56 * 10
After retuning X number of oranges, the average is 52 * (10 - X)

So the difference of these two should yield the contribution of giving back X oranges.

60 * X = 560 - 52(10 -X)
Solving: X = 5
2838
solve this

Q3:
Each participant in a certain study was assigned a sequence of 3 different letters from the
set {A, B, C, D, E, F, G, H}. If no sequence was assigned to more than one participant
and if 36 of the possible sequences were not assigned, what was the number of
participants in the study? (Note, for example, that the sequence A, B, C is different from
the sequence C, B, A.)
A. 20
B. 92
C. 300
D. 372
E. 476


IMO: C

8P3 is the number of sequences possible. Its a P instead of a C as the order in which the letters appear is important.
36 were not assigned out of 8P3,
So the ones that got assigned are: 8P3 - 36 = 336 -36 = 300
2839
solve this

Q3:
Each participant in a certain study was assigned a sequence of 3 different letters from the
set {A, B, C, D, E, F, G, H}. If no sequence was assigned to more than one participant
and if 36 of the possible sequences were not assigned, what was the number of
participants in the study? (Note, for example, that the sequence A, B, C is different from
the sequence C, B, A.)
A. 20
B. 92
C. 300
D. 372
E. 476


My Take is C

8c3*3 -36= 20
2840
If a committee of 3 people is to be selected from among 5 married couples so that the committee does not include two people who are married to each other, how many such committees are possible?

A. 20
B. 40
C. 50
D. 80
E.120