Math sucks....?

Question

I'm homeschooled and I send tests via email. Unfortunately, my teachers don't send back the right answers to questions that were wrong. I'm curious about these two that I missed. Can anyone tell me the right answers?

1. You are at the music store to buy some CDs. You have $45 to spend and the store sells CDs for $12.99 each. Write an inequality that represents the number, n, of CDs that you can buy without spending more money than you have.

2. solve the inequality: 6 < x + 4 <= 11

Answer 1

1)
Each CD costs $12.99.

Roughly the number you can buy is $45/$12.99 = 3.46...

so the maximum number of CDs you can buy is 3 and the minimum is that you don't have to buy any at all.

If n is the number of CDs then 0<= n <= 3.

2)
6 < x + 4 <= 11

This is actually two inequalities in one.

6 < x + 4 ___and___x + 4 <= 11

For the first one, take 4 from both sides

We get 2 < x .

For the second one, take 4 from both sides.

x <= 7

You are left with that 2 < x <= 7.

Answer 2

Math doesn't suck. It's PEOPLE that suck AT DOING it.

1. If you buy "n" CDs for 12.99 each then excluding tax, the total amount you spend on cds is 12.99n. You can't spend more than $45, so the inequality is
12.99n <= 45

2. Break this up into two inequalities:
6 < x+4 and x+4 <=11

Now subtract 4 from both:
2 < x and x <=7

Combine these to make one inequality
2 < x <= 7.

In this case you didn't really have to break up the inequality, but breaking up the inequality might be handy if for example you have to do different opperations to both of them.

Answer 3

The question is how many CDs will still cost less than or equal to $45.
12.99*n ≤ 45
n ≤ 45/12.99
n≤ 3.46
Since you can't buy a part of a CD, you'll have to be happy with 3 CDs and some change.

2. 6 (6-4) 2

Answer 4

1) money for CD's must be less than $$ on hand.... let #of CD's be x and cash be $$

divide cd's into cash... ( $$/ cd)
if solution is >1, you are able to purchace the Whole number amount ... the decimal is the remainder ....
(example... 45 / 12.99 = 3.4620 ..... i can buy 3 cd's and have .4620 / 12.99 left over as change (6.00)

so (n*cd) < or= ($$$)


as for the inequality ....
subtract 4 from each element of the eq ....
2 < x <= 7 .... so x must be between 2 & 7 (7 included)

Answer 5

1. 12.99N (is less than or equal to) 45

2. 2 < x <= 7
[is that what you were supposed to do? Lol]
I just made it two equations and solved them to find all possible values of X.

6 < x+4 and x+4<=11

Answer 6

1. You can buy less than four, so the CDs are n<4.
2. x=7 as that is the only value that it can have.