GMAT Problem Solving Discussions

MBA
3441
$1=100 cents
$3.20= 320 cents
$5.80= 580 cents

Now,as per the ques:
320+5x=580-0.414x
On solving we get x=48.03
Put this value in 320+5(48.03)=560.15 cents or $5.60
Similarily, 580-0.414(48.03)=560.11 cents or $5.60

Hence Answer is E.

Regards,
Neha


@everyone

But i guess there r 2 variables in this equation.
one is x and the other is no. of days
so how could u solve it using a single equation?
3442
@everyone

But i guess there r 2 variables in this equation.
one is x and the other is no. of days
so how could u solve it using a single equation?



Sorry dude, but i couldn't get two eqs. i agree with your point, but probably can't put it in mathematical terms. you tell what's the way to solve, if this is wrong?


Regards,
Neha
3443
Guys,
Try this one

The price of a bushel of corn is currently $3.20, and the price of a peck of wheat is $5.80. The price of corn is increasing at a constant rate of 5x cents per day while the price of wheat is decreasing at a constant rate of 0.414x cents per day. What is the approximate price when a bushel of corn costs the same amount as a peck of wheat?
(A) $4.50
(B) $5.10
(C) $5.30
(D) $5.50
(E) $5.60




what does the variable "x" represent in this problem? if that is known the problem can be solved, otherwise i will stick with option (E).
3444
Guys,

The price of a bushel of corn is currently $3.20, and the price of a peck of wheat is $5.80. The price of corn is increasing at a constant rate of 5x cents per day while the price of wheat is decreasing at a constant rate of 0.414x cents per day. What is the approximate price when a bushel of corn costs the same amount as a peck of wheat?
(A) $4.50
(B) $5.10
(C) $5.30
(D) $5.50
(E) $5.60


Now,as per the ques:
320+5x=580-0.414x
On solving we get x=48.03
Put this value in 320+5(48.03)=560.15 cents or $5.60
Similarily, 580-0.414(48.03)=560.11 cents or $5.60

Hence Answer is E.

Regards,
Neha

@everyone

But i guess there r 2 variables in this equation.
one is x and the other is no. of days
so how could u solve it using a single equation?

nemo1 Says
what does the variable "x" represent in this problem? if that is known the problem can be solved, otherwise i will stick with option (E).


IMO Ans E ...
i guess question is not ambiguous...
Yes, vpitc, there are indeed 2 parameters...one is rate of growth/ decline and the other is no of days ...

Actually, both the parameters are covered by a single variable x ...

i dont find any flaw in neha's approach..
To elaborate ...value of x is 48.03...

Now, let the rate of increase / decrease be m
and no of days is n

So, x = mn ....so if no of days increases the rate of increase/ decrease decreases such that product remains constant ...

like it cud be a day and m = 48
or it cud be 2 days i.e n=2 and m=24 and so on so forth ...

so, actually bifurcation of rate and no of days is not needed...this single variable x takes care of both...

Hope this helps ...
3445

@Bhavin, Neha, Nemo1

Yes im convinced with ur solution.OA is e
Indeed what they mean by 5x is the price of corn is increasing @ of 5 cents per day or in multiples of 5 each day.Otherwise a soln is not possible
Thanks

3446
try this one,
If P represents the product of the first 15 positive integers, then P is not a multiple of:
a) 99 b) 84 c) 72 d) 65 e) 57
3447

Posted in error

3448
try this one,
If P represents the product of the first 15 positive integers, then P is not a multiple of:
a) 99 b) 84 c) 72 d) 65 e) 57


a. 99 = 9 x 11
b. 84 = 7 x 12
c. 72 = 8 x 9
d. 65 = 5 x 13
e. 57 = 3 x 19 ( Answer )
3449
a. 99 = 9 x 11
b. 84 = 7 x 12
c. 72 = 8 x 9
d. 65 = 5 x 13
e. 57 = 3 x 19 ( Answer )


ya u r right OA is e
3450
try this,
If Bob and Jen are two of 5 participants in a race, how many different ways can the race finish where Jen always finishes in front of Bob?
a)24
b)60
c)120
d)36
e)48
3451
try this,
If Bob and Jen are two of 5 participants in a race, how many different ways can the race finish where Jen always finishes in front of Bob?
a)24
b)60
c)120
d)36
e)48


Total ways = 5! = 120
In half Jen is going to be ahead of Bob ...

Hence 60 ...Option B
3452
try this,
If Bob and Jen are two of 5 participants in a race, how many different ways can the race finish where Jen always finishes in front of Bob?
a)24
b)60
c)120
d)36
e)48


4! = 24 = (a)
3453
Total ways = 5! = 120
In half Jen is going to be ahead of Bob ...

Hence 60 ...Option B


dude, u r right OA is b
solid explanation...
3454
try this,
If Bob and Jen are two of 5 participants in a race, how many different ways can the race finish where Jen always finishes in front of Bob?
a)24
b)60
c)120
d)36
e)48

Total ways = 5! = 120
In half Jen is going to be ahead of Bob ...

Hence 60 ...Option B

dude, u r right OA is b
solid explanation...


Logically, it was very simple ...
mathematical proof ...

When Jen is in position 1; bob can take 4 places and rest 3!
When Jen is in position 2; bob can take 3 places and rest 3!
When Jen is in position 3; bob can take 2 places and rest 3!
When Jen is in position 4; bob can take 1 place and rest 3!

Hence total = (4+3+2+1) 3! = 60

Generalized way of n people ...
Total such that 1 is ahead of the other is summation (n-1) * (n-2)!

=(n-1)n / 2 * (n-2)! = n! / 2 ...ie half the total
3455
Logically, it was very simple ...
mathematical proof ...

When Jen is in position 1; bob can take 4 places and rest 3!
When Jen is in position 2; bob can take 3 places and rest 3!
When Jen is in position 3; bob can take 2 places and rest 3!
When Jen is in position 4; bob can take 1 place and rest 3!

Hence total = (4+3+2+1) 3! = 60

Generalized way of n people ...
Total such that 1 is ahead of the other is summation (n-1) * (n-2)!

=(n-1)n / 2 * (n-2)! = n! / 2 ...ie half the total


Dude,
i was convinced with ur original explanation
3456
  1. is the answer ,


coz f(-2) = f(-2 * -2) = f (4)

then f(4) = f(4*4) = f(6)

so f(16)-f(-2) = 0

correct me if i am wrong !!

well you are right but i'm still confused...can you explain in detail. Why are we solving only f(-2)..why not f(16) also.

3457
If function satisfies for all , which of the following must be true?








  1. is the answer ,
coz f(-2) = f(-2 * -2) = f (4)

then f(4) = f(4*4) = f(6)

so f(16)-f(-2) = 0

correct me if i am wrong !!

shalinikrishna2 Says
well you are right but i'm still confused...can you explain in detail. Why are we solving only f(-2)..why not f(16) also.


Hey Shalini,

f(-2) is already explained above,and you also agree with that. Will solve with using f(16)

f(16)=f(16*16)=f(256)
Now we want f(-2) to be equal to f(256)=f(16)

f(-2)=f(-2*-2)=f(4)
f(4)=f(4*4)=f(16)
f(16)=f(16*16)=f(256)

Hence f(16)=f(256)=f(-2)
So by both ways, we have f(16)-f(-2)=0

Hope it clears your doubt.

Regards,
Neha
3458

try this

Fox jeans regularly sell for $15 a pair and Pony jeans regularly sell for $18 a pair. During a sale these regular unit prices are discounted at different rates so that a total of $9 is saved by purchasing 5 pairs of jeans: 3 pairs of Fox jeans and 2 pairs of Pony jeans. If the sum of the two discounts rates is 22 percent, what is the discount rate on Pony jeans?
(A) 9%
(B) 10%
(C) 11%
(D) 12%
(E) 15%

give the explanation as well

3459
try this

Fox jeans regularly sell for $15 a pair and Pony jeans regularly sell for $18 a pair. During a sale these regular unit prices are discounted at different rates so that a total of $9 is saved by purchasing 5 pairs of jeans: 3 pairs of Fox jeans and 2 pairs of Pony jeans. If the sum of the two discounts rates is 22 percent, what is the discount rate on Pony jeans?
(A) 9%
(B) 10%
(C) 11%
(D) 12%
(E) 15%

give the explanation as well


Is the answer B?
if the answer is right then will give the explaination
3460
Is the answer B?
if the answer is right then will give the explaination


ya u r right OA is b