Challenge your brains! Can you solve this problem?

[kickman]

I met this problem in my interview.I'd like to share it with you.

By selling a product a seller is gaining 10% on selling price. If he sells that product Rs.80 less, he would have been losing 10%. What is the cost price?

[Atzar]

Rs.80 means 80 rupees, right?  That's what Google and Wikipedia seem to think, but I'm not really familiar with Indian currency so I could easily be wrong.  I'm just going to write it out as "80 rupees" in the rest of this post, so if that's not proper notation, I apologize.

Mathematically, it's not a particularly difficult question.  If 80 rupees is the difference between gaining 10% and losing 10%, then 80 rupees is 20% of the selling price.  80 * 5 is 400 rupees, so the original cost price is 400 rupees.

I'm pretty sure I got that right...

[Cman]

Rs.80 means 80 rupees, right?  That's what Google and Wikipedia seem to think, but I'm not really familiar with Indian currency so I could easily be wrong.  I'm just going to write it out as "80 rupees" in the rest of this post, so if that's not proper notation, I apologize.

Mathematically, it's not a particularly difficult question.  If 80 rupees is the difference between gaining 10% and losing 10%, then 80 rupees is 20% of the selling price.  80 * 5 is 400 rupees, so the original cost price is 400 rupees.

I'm pretty sure I got that right...

Agreed that the answer is 400 rupees.

Set it up in two equations:
S is selling price and C is cost:
S = 1.1C
S-80 = 0.9C
if you subtract bottom from top you get:
80 = 0.2C
Solving, you get C = 400

[Redz]

I was one of 2 in my current Math class to get this one right.

Three travelers stopped at an inn for supper. The innkeeper could offer only baked potatoes. While the potatoes were baking, the weary travelers fell asleep. Soon, one of them woke up, saw the dish of potatoes and took a third of them without waking up the others. Later the second one woke up, saw the dish, and ate a third of the remaining potatoes. Later the third one did the same. When all three were sleeping once again, the innkeeper cleared the table and found 8 potatoes left. How many potatoes were originally on the table?

[Fan from VT]

I was one of 2 in my current Math class to get this one right.

Three travelers stopped at an inn for supper. The innkeeper could offer only baked potatoes. While the potatoes were baking, the weary travelers fell asleep. Soon, one of them woke up, saw the dish of potatoes and took a third of them without waking up the others. Later the second one woke up, saw the dish, and ate a third of the remaining potatoes. Later the third one did the same. When all three were sleeping once again, the innkeeper cleared the table and found 8 potatoes left. How many potatoes were originally on the table?

should be 27.

27 - 1/3 (9) = 18 - 1/3 (6) = 12 - 1/3 (4)= 8

[Redz]

I was one of 2 in my current Math class to get this one right.

Three travelers stopped at an inn for supper. The innkeeper could offer only baked potatoes. While the potatoes were baking, the weary travelers fell asleep. Soon, one of them woke up, saw the dish of potatoes and took a third of them without waking up the others. Later the second one woke up, saw the dish, and ate a third of the remaining potatoes. Later the third one did the same. When all three were sleeping once again, the innkeeper cleared the table and found 8 potatoes left. How many potatoes were originally on the table?

should be 27.

27 - 1/3 (9) = 18 - 1/3 (6) = 12 - 1/3 (4)= 8

yes sir

[Redz]

how did you arrive at your answer VT?

I drew a pie charts and worked from the end to the beginning

[yall hate]

I was one of 2 in my current Math class to get this one right.

Three travelers stopped at an inn for supper. The innkeeper could offer only baked potatoes. While the potatoes were baking, the weary travelers fell asleep. Soon, one of them woke up, saw the dish of potatoes and took a third of them without waking up the others. Later the second one woke up, saw the dish, and ate a third of the remaining potatoes. Later the third one did the same. When all three were sleeping once again, the innkeeper cleared the table and found 8 potatoes left. How many potatoes were originally on the table?

18

edit - woops, thought there were only 2 people taking 1/3...haha, I actually started with 27 first, and did the 1/3, 1/3, in my head, but since I for some reason dont know how to read, realized that was too many.  But I would have had it on my first educated guess had I learned to read. lol

[Redz]

I was one of 2 in my current Math class to get this one right.

Three travelers stopped at an inn for supper. The innkeeper could offer only baked potatoes. While the potatoes were baking, the weary travelers fell asleep. Soon, one of them woke up, saw the dish of potatoes and took a third of them without waking up the others. Later the second one woke up, saw the dish, and ate a third of the remaining potatoes. Later the third one did the same. When all three were sleeping once again, the innkeeper cleared the table and found 8 potatoes left. How many potatoes were originally on the table?

18

neggie

[Redz]

My class this weekend was very big into honoring students various methods of solving math problems (not being a stickler for one method like I when I was in school).

Let me know how you guys figured it out. 

[fairweatherfan]

how did you arrive at your answer VT?

I drew a pie charts and worked from the end to the beginning

Take 1/3rd of a quantity away and the remainder is 2/3rds of the original, so the original is 1 1/2x the remaining amount.

3/2 (8 ) = 12
3/2 (12) = 18
3/2 (18) = 27

[Roy Hobbs]

I was one of 2 in my current Math class to get this one right.

Three travelers stopped at an inn for supper. The innkeeper could offer only baked potatoes. While the potatoes were baking, the weary travelers fell asleep. Soon, one of them woke up, saw the dish of potatoes and took a third of them without waking up the others. Later the second one woke up, saw the dish, and ate a third of the remaining potatoes. Later the third one did the same. When all three were sleeping once again, the innkeeper cleared the table and found 8 potatoes left. How many potatoes were originally on the table?

should be 27.

27 - 1/3 (9) = 18 - 1/3 (6) = 12 - 1/3 (4)= 8

Yep, that's what I came up with, too.  It probably took me a little longer than it took you, though.

[yall hate]

I always liked this one (From Die Hard 3).  Not too difficult at all, but fun

To stop a bomb going off, McClane and Zeus have to measure out exactly four gallons of water from a fountain using a three gallon jug and a five gallon jug.

So how do you do it?

[FatKidsDad]

I always liked this one (From Die Hard 3).  Not too difficult at all, but fun

To stop a bomb going off, McClane and Zeus have to measure out exactly four gallons of water from a fountain using a three gallon jug and a five gallon jug.

So how do you do it?

Fill the five and pour it into the three.

That leaves 2 in the five gallon jug.

Dump out the three gallon jug and transfer the two gallons from the five to the three

Fill the five gallon jug and pour from it into the three gallon jug until it is full.

Four gallons remaining in the five gallon jug.

[Chris]

I always liked this one (From Die Hard 3).  Not too difficult at all, but fun

To stop a bomb going off, McClane and Zeus have to measure out exactly four gallons of water from a fountain using a three gallon jug and a five gallon jug.

So how do you do it?

Fill up 3 gallon, and pour into 5 gallon.  Then fill it up again, and pour 2 of the 3 gallons to fill up the 5 gallon, leaving 1 gallon in the 3 gallon.  Empty the 5 gallon, and then pour the 1 gallon in there.  Refill the 3 gallon, and pour into the 5 gallon, and you have 4 gallons.