please help with brain teasers!!!!!?

Question

also, how u got it
1.A bookstore has a nice discount policy. If you buy a $20 book today, you get a 2% discount on your next buy. If u buy a $15 book, u get a 1.5%discnt on ur next buy. If you have to buy 3 books costing $10, $20, $30, you could buy the $30 book 2day, the $10 tomorrow (you'll get a 3% discnt), and the $20 the day after (1% discnt). Or u could buy the 30% book and the $20 book today, and the $10 tomorrow (with 5% dis) What is the cheapest way to buy 5 books costing $10, $20, $30,$40,$50?
2. An indiscreet young man asks his beautiful math teacher her age. She says," todays date is my age, although b4 this week is over there will be another day with a date 1/5 of the new age that i'll be." what's her sign of the zodiac?

Answer 1

1. You are going to get at most 4 of {1% off, 2% off, 3% off, 4% off, 5% off}, because you won't get the discount from the last book you buy.
If the last book you buy is $50, then you may as well use them all on the last book, getting a total discount of $5.
If you don't buy the $50 book last, you may as well use up all the discounts you can on the $50 book, and the 5% discount on the last book.
So just go through the cases:
Buy 40 last: use 1+2+3 on $50, and 5 on $40
Buy 30 last: use 1+2+4 on $50, and 5 on $30
Buy 20 last: use 1+3+4 on $50, and 5 on $20
Buy 10 last: use 2+3+4 on $50, and 5 on $10

None of them beats the $5 discount (though the first option equals it :))

In case you're not sure why you can do that - once you know what discounts you're allowed, you are going to use them on something - so why not the largest value book? Then you're just left with the 5% discount on the last book.

2. Lets say her age is now is x.

I'm going to assume when she said 'new age', she means it will be a different age, otherwise taking the 30th of any month with 30 days will work.
We need her new age (x+1) to be a multiple of 5.
We also need x to be within a week of the end of the month, otherwise the new date will be far too big.
So the only possibilities are 24 or 29.
If her age is 24, then she'll turn 25 and the date within a week must be the 5th - thats impossible.
If her age is 29, then she'll turn 30 and the date within a week must be the 6th. Thats only possible if its February 29th in a leap year, otherwise the 6th is at least 7 days away.

Thus her birthday is in the first week of march, so she is Pisces, I think it is.

Answer 2

both questions require more info...

However the 1st one if you get discounts on more than 1 item the next day would have you purchase $70 or $80 worth of books today and buy the rest the next day and you'd save $5.60. If you could only save on 1 item, the best way would be to buy the $10 through the $40 book today to save 10 percent on the $50 book and save $5.00

The object is to save the most money so you want the largest discount on the most expensive items. If you had enough items (much more than 5) to purchase $1000 worth of books you'd get any new book free. Since you only have those 5 books, 14 percent is the largest discount you can get on any one item, but $1.40 isn't nearly as much as saving 10 percent on the $50 one.

The 2nd problem asks for you to find her age now and later in the week so you can determine her zodiac sign.

The only way this problem will work is if you are in the last week of one month and move into the beginning of the next to find an age that's 1/5 of her new one. This means her birthday is in the current week. with only 12 possible weeks in the year to choose from you need a date combination that adds to a reasonable teacher's age and can be divided by 5. If you had the day by itself. The only thing that would work would be a 30 and a 6. However, she has to be 29 now to become 30 later which would take 8 days. Therefore you need the month, too. The best combination is May 29th leading into June 1.
5 + 29 becoming 6 + 1. So, she's 34 now and will be 35 which 7 is one fifth of. Therefore her zodiac sign would be: Gemini

Answer 3

i think she is a capricorn....

12/26/06 = 12+26+06 = 44 (she will be 45)
01/01/07 = 1+1+7 = 9, which is one fifth of 45

That was hard! The only two schemes I could think of was a changing year (a nice way to say happy new year) and something involving a leap year.

heh, we got three good answers. I am curious what the answer they give is. Please keep us informed.

Answer 4

this can be solved by usind derivative. make an equation and find its derivative, then solve for thevariable.

I can't clearly understand ur question. if i buy a $30 book, the discount is 2% or 3%? how?

Answer 5

one million. not something because of the fact there is not any oxygen for the flame to seize on 2. nevertheless Mt. Everest because of the fact that is not in simple terms like the mountain wasnt there anymore 3.i could be protecting the letter b in my right hand because of the fact this is a reflect image so that's the alternative of what i see 4. mom. that is because of the fact if my dads sister has a sister in regulation, its via marriage and so this is maximum probable from her sister, that's my dad. (if that is sensible in any respect??)XD