Math optimization riddle












1












$begingroup$



You have been given the task of transporting 3,000 apples 1,000 miles
from Appleland to Bananaville. Your truck can carry 1,000 apples at a
time. Every time you travel a mile towards Bananaville you must pay a
tax of 1 apple but you pay nothing when going in the other direction
(towards Appleland). What is highest number of apples you can get to
Bananaville




The answer is $boxed{833}$. However, I don't understand how to obtain this answer. Also, is there any way to show that the answer is optimal?



I have seen a riddle similar to this before, and I think the trick is to move $1000$ apples towards a stopping point, come back, get more to that stopping point, and so on. I can't figure this one out, though.










share|cite|improve this question









$endgroup$












  • $begingroup$
    Doing a quick Google search will get you a method for $833$. See for example goodriddlesnow.com/riddles/hard/page:5/sort:Riddle.difficulty/… . This doesn't prove optimality though
    $endgroup$
    – pwerth
    Jan 17 at 20:22
















1












$begingroup$



You have been given the task of transporting 3,000 apples 1,000 miles
from Appleland to Bananaville. Your truck can carry 1,000 apples at a
time. Every time you travel a mile towards Bananaville you must pay a
tax of 1 apple but you pay nothing when going in the other direction
(towards Appleland). What is highest number of apples you can get to
Bananaville




The answer is $boxed{833}$. However, I don't understand how to obtain this answer. Also, is there any way to show that the answer is optimal?



I have seen a riddle similar to this before, and I think the trick is to move $1000$ apples towards a stopping point, come back, get more to that stopping point, and so on. I can't figure this one out, though.










share|cite|improve this question









$endgroup$












  • $begingroup$
    Doing a quick Google search will get you a method for $833$. See for example goodriddlesnow.com/riddles/hard/page:5/sort:Riddle.difficulty/… . This doesn't prove optimality though
    $endgroup$
    – pwerth
    Jan 17 at 20:22














1












1








1





$begingroup$



You have been given the task of transporting 3,000 apples 1,000 miles
from Appleland to Bananaville. Your truck can carry 1,000 apples at a
time. Every time you travel a mile towards Bananaville you must pay a
tax of 1 apple but you pay nothing when going in the other direction
(towards Appleland). What is highest number of apples you can get to
Bananaville




The answer is $boxed{833}$. However, I don't understand how to obtain this answer. Also, is there any way to show that the answer is optimal?



I have seen a riddle similar to this before, and I think the trick is to move $1000$ apples towards a stopping point, come back, get more to that stopping point, and so on. I can't figure this one out, though.










share|cite|improve this question









$endgroup$





You have been given the task of transporting 3,000 apples 1,000 miles
from Appleland to Bananaville. Your truck can carry 1,000 apples at a
time. Every time you travel a mile towards Bananaville you must pay a
tax of 1 apple but you pay nothing when going in the other direction
(towards Appleland). What is highest number of apples you can get to
Bananaville




The answer is $boxed{833}$. However, I don't understand how to obtain this answer. Also, is there any way to show that the answer is optimal?



I have seen a riddle similar to this before, and I think the trick is to move $1000$ apples towards a stopping point, come back, get more to that stopping point, and so on. I can't figure this one out, though.







optimization puzzle






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share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Jan 17 at 20:11







user614735



















  • $begingroup$
    Doing a quick Google search will get you a method for $833$. See for example goodriddlesnow.com/riddles/hard/page:5/sort:Riddle.difficulty/… . This doesn't prove optimality though
    $endgroup$
    – pwerth
    Jan 17 at 20:22


















  • $begingroup$
    Doing a quick Google search will get you a method for $833$. See for example goodriddlesnow.com/riddles/hard/page:5/sort:Riddle.difficulty/… . This doesn't prove optimality though
    $endgroup$
    – pwerth
    Jan 17 at 20:22
















$begingroup$
Doing a quick Google search will get you a method for $833$. See for example goodriddlesnow.com/riddles/hard/page:5/sort:Riddle.difficulty/… . This doesn't prove optimality though
$endgroup$
– pwerth
Jan 17 at 20:22




$begingroup$
Doing a quick Google search will get you a method for $833$. See for example goodriddlesnow.com/riddles/hard/page:5/sort:Riddle.difficulty/… . This doesn't prove optimality though
$endgroup$
– pwerth
Jan 17 at 20:22










1 Answer
1






active

oldest

votes


















2












$begingroup$

The truck should be as full as possible, so as soon as you can combine multiple truckloads into one, you should do so. The first time that happens is after 333 1/3 miles. You can get the apples to the 333 1/3 mile marker in 3 truckloads, pay 1000 in tax, and be left with 2000 apples. Then you can go another 500 miles before you can combine truckloads again. Hauling 2000 apples in two truckloads over 500 miles costs you 1000 in tax, leaving you with 1000 apples at the 833 1/3 mile marker. The remaining 166 2/3 miles can be driven with one truckload, leaving you with 1000-166 2/3=833 1/3 apples.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    how do i show this is optimal?
    $endgroup$
    – user614735
    Jan 17 at 21:31










  • $begingroup$
    @stackofhay42 the rationale is in the first sentence.
    $endgroup$
    – LinAlg
    Jan 17 at 21:44












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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes









2












$begingroup$

The truck should be as full as possible, so as soon as you can combine multiple truckloads into one, you should do so. The first time that happens is after 333 1/3 miles. You can get the apples to the 333 1/3 mile marker in 3 truckloads, pay 1000 in tax, and be left with 2000 apples. Then you can go another 500 miles before you can combine truckloads again. Hauling 2000 apples in two truckloads over 500 miles costs you 1000 in tax, leaving you with 1000 apples at the 833 1/3 mile marker. The remaining 166 2/3 miles can be driven with one truckload, leaving you with 1000-166 2/3=833 1/3 apples.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    how do i show this is optimal?
    $endgroup$
    – user614735
    Jan 17 at 21:31










  • $begingroup$
    @stackofhay42 the rationale is in the first sentence.
    $endgroup$
    – LinAlg
    Jan 17 at 21:44
















2












$begingroup$

The truck should be as full as possible, so as soon as you can combine multiple truckloads into one, you should do so. The first time that happens is after 333 1/3 miles. You can get the apples to the 333 1/3 mile marker in 3 truckloads, pay 1000 in tax, and be left with 2000 apples. Then you can go another 500 miles before you can combine truckloads again. Hauling 2000 apples in two truckloads over 500 miles costs you 1000 in tax, leaving you with 1000 apples at the 833 1/3 mile marker. The remaining 166 2/3 miles can be driven with one truckload, leaving you with 1000-166 2/3=833 1/3 apples.






share|cite|improve this answer









$endgroup$













  • $begingroup$
    how do i show this is optimal?
    $endgroup$
    – user614735
    Jan 17 at 21:31










  • $begingroup$
    @stackofhay42 the rationale is in the first sentence.
    $endgroup$
    – LinAlg
    Jan 17 at 21:44














2












2








2





$begingroup$

The truck should be as full as possible, so as soon as you can combine multiple truckloads into one, you should do so. The first time that happens is after 333 1/3 miles. You can get the apples to the 333 1/3 mile marker in 3 truckloads, pay 1000 in tax, and be left with 2000 apples. Then you can go another 500 miles before you can combine truckloads again. Hauling 2000 apples in two truckloads over 500 miles costs you 1000 in tax, leaving you with 1000 apples at the 833 1/3 mile marker. The remaining 166 2/3 miles can be driven with one truckload, leaving you with 1000-166 2/3=833 1/3 apples.






share|cite|improve this answer









$endgroup$



The truck should be as full as possible, so as soon as you can combine multiple truckloads into one, you should do so. The first time that happens is after 333 1/3 miles. You can get the apples to the 333 1/3 mile marker in 3 truckloads, pay 1000 in tax, and be left with 2000 apples. Then you can go another 500 miles before you can combine truckloads again. Hauling 2000 apples in two truckloads over 500 miles costs you 1000 in tax, leaving you with 1000 apples at the 833 1/3 mile marker. The remaining 166 2/3 miles can be driven with one truckload, leaving you with 1000-166 2/3=833 1/3 apples.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Jan 17 at 20:26









LinAlgLinAlg

10.1k1521




10.1k1521












  • $begingroup$
    how do i show this is optimal?
    $endgroup$
    – user614735
    Jan 17 at 21:31










  • $begingroup$
    @stackofhay42 the rationale is in the first sentence.
    $endgroup$
    – LinAlg
    Jan 17 at 21:44


















  • $begingroup$
    how do i show this is optimal?
    $endgroup$
    – user614735
    Jan 17 at 21:31










  • $begingroup$
    @stackofhay42 the rationale is in the first sentence.
    $endgroup$
    – LinAlg
    Jan 17 at 21:44
















$begingroup$
how do i show this is optimal?
$endgroup$
– user614735
Jan 17 at 21:31




$begingroup$
how do i show this is optimal?
$endgroup$
– user614735
Jan 17 at 21:31












$begingroup$
@stackofhay42 the rationale is in the first sentence.
$endgroup$
– LinAlg
Jan 17 at 21:44




$begingroup$
@stackofhay42 the rationale is in the first sentence.
$endgroup$
– LinAlg
Jan 17 at 21:44


















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