I'm posting one puzzle, riddle, math, or statistical problem a day. Try to answer each one and post your answers in the comments section. I'll post the answer the next day. Even if you have the same answer as someone else, feel free to put up your answer, too!
Tuesday, August 07, 2012
Drinking Soda is Bad For Your Teeth
Joan likes drinking soda. She can recycle five empty soda bottles and get a full one at the store. As part of the town clean up, she found 77 empty bottles. How many bottles of soda will she be able to drink in total?
Turn in 75 empties to get 15 full, save the extra 2 for later. Drink those 15 and turn them in for 3 full. Drink those 3 and turn them in along with the two extra and get 1 full.
For every five she takes back she gets one in return. Starting with 77, subtract 5 and then add one. Continue doing that, until she is down to her last 5 empty bottles. For those last 5 she gets another full bottle, and can drink that too.
OR
Subract 4 from 77, and then 4 from 73, and then... Until you're down to 9. 9-4=5, 5-4=1 (One left, which she drinks).
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19.
ReplyDeleteTurn in 75 empties to get 15 full, save the extra 2 for later.
Drink those 15 and turn them in for 3 full.
Drink those 3 and turn them in along with the two extra and get 1 full.
15+3+1 = 19
Andy got it. 19
Delete(jim May)
She can drink 20, no?
ReplyDeleteFor every five she takes back she gets one in return. Starting with 77, subtract 5 and then add one. Continue doing that, until she is down to her last 5 empty bottles. For those last 5 she gets another full bottle, and can drink that too.
OR
Subract 4 from 77, and then 4 from 73, and then... Until you're down to 9. 9-4=5, 5-4=1 (One left, which she drinks).
I agree with 19.
ReplyDeleteRodney S.
19 is the answer. Nice work Andy.
ReplyDelete