Brain Teaser!

[calbear2000]

Let see if anyone gets this:

#A customer at a 7-11 store selected four items to buy, and was told that
#the cost was $7.11. He was curious that the cost was the same as the store
#name, so he inquired as to how the figure was derived. The clerk said that
#he had simply multiplied the prices of the four individual items. The
#customer protested that the four prices should have been ADDED, not
#MULTIPLIED. The clerk said that that was OK with him, but, the result was
#still the same: exactly $7.11. What were the prices of the four items?

 

[Ns1]

n/m

 

[J0Y]

$0.83
$1.59
$2.01
$2.68

 

[Ameesh]

<< $0.83
$1.59
$2.01
$2.68 >>



nice

 

[calbear2000]

<< $0.83
$1.59
$2.01
$2.68 >>



Good. Thats one possible pseduo-correct answer But there is only one EXACT answer whose product is exactly 7.11

Of course your answer is right too, because 7.1089 is essentially $7.11 But if you accept that, you'd also accept 2.75, 2.17, 1.18, 1.01

 

[Ameesh]

<<

<< $0.83
$1.59
$2.01
$2.68 >>



Good. Thats one possible pseduo-correct answer But there is only one EXACT answer whose product is exactly 7.11

Of course your answer is right too, because 7.1089 is essentially $7.11 But if you accept that, you'd also accept 2.75, 2.17, 1.18, 1.01 >>



lol i was writing a program to find the solution and you guys wrote 2 down!

 

[calbear2000]

Did your program find these possible solutions as well?

2.75, 2.17, 1.18, 1.01
2.68, 2.26, 1.14, 1.03
2.33, 2.56, 1.31, 0.91
2.28, 2.51, 1.48, 0.84
2.22, 2.67, 1.29, 0.93
1.99, 2.89, 1.19, 1.04
1.31, 3.18, 1.4, 1.22

lol

So many more combinations... but of course, I left out the one exact answer

Perl is so awesome

 

[dfi]

Are you asking us to write a program to solve this? Or are you saying there is a way to find the answer by hand?

dfi

 

[darkjester]

<< Are you asking us to write a program to solve this? Or are you saying there is a way to find the answer by hand? >>


Yeah, I'd be interested in knowing how to derive this answer using some method other than brute force. Is there some mathematical process to get these answers?

 

[dionx]

<< Yeah, I'd be interested in knowing how to derive this answer using some method other than brute force. Is there some mathematical process to get these answers? >>



the closest thing i can think of is to:

w + x + y + z = 7.11
w * x * y * z = 7.11

w = 7.11/(x*y*z)
x = 7.11/(w*y*z)
y = 7.11/(w*x*z)
z = 7.11/(w*x*y)

so if you were to plug this into excel, just hold "w" constant with the formula, but manipulate the 3 other numbers. what to do from this point.. guess and check.. using excel should simplify the check process. i dunno. ????????????

 

[Time2Kill]

Answer is contained below...dont look if you dont want to see it




































1.20
1.25
1.50
3.16

Too easy