Need help with some math problems.

These are some math problems from my class that’s been driving me a little crazy 1.How much water must be added to 20 ounces of a 15% solution of alcohol to reduce it to a solution that is 10% alcohol?
2. A basketball team averages 98 points in its first three games. How many points must it score in the next game in order to have a 100-point average overall?
Now for the second question, I understand that
a+b+c
——- = 98
3
But i don’t really get where to go from there.
maybe
a+b+c+d
———– =100
4
I might add some more questions because I’m doing this whole packet…
I don’t need straight out answers, but if you do give me them, please explain how you got it.
Thanks in advance :]
Answer #1
Are you serious?
Answer #2
If I wasn’t serious then I wouldn’t be asking them now would I? Writing is my strong suit, so I suck at math.
Answer #3
Well, for your first one:
20*0.15 = 3 ounces of alcohol
You want this to make up 10% of the final solution so the final solution is 3/0.1 = 30
So 30-20 = 10, you need 10 more ounces of water
For the second one you’re getting too bogged down worry what a,b and c are. It doesn’t matter. Because they average 98 they can all just be set to 98. so then you get (98+98+98+d)/4=100 so d = 106
Hope that all makes sense
Answer #4
ok then. You are right for the second basketball question it is 400 – (98 x 3)=106 and first one is 10
Answer #5
Thanks :O
I have another one >.<
Five printing presses can print a newspaper in six hours. If only three of the presses are operating, how long, in hours, will it take them to do the same job?
I understand that you have to use some kind of proportion
maybe 5= 1 newspaper for every 6 hours
3= 1 newspaper for ever x hours…..
But I don’t really know where to go from there.
Thanks
Answer #6
Right ok (I’m really bored this evening!)
five printing presses print 1/6 of a paper an hour so one printing press prints 1/6*1/5 of a paper an hour (1/30). Three printing presses print 3/30 of a paper an hour so it will take 30/3 to print a paper – 10 hours.
Answer #7
the answer is 10 5 presses do 30 job in 6 hours (5×6=30) 3 presses do 30 job in 10 hours (30/3 = 10)
Answer #8
Looks like Gimpy is faster than me
Answer #9
So basically, if you get a question like that, you multiply the two rates, then you multiply by the number of x your trying to find the rate of, then you divide.. ok :]
Wow you must be bored lol.
Mhmm I have yet to find any more questions that I can not do…
Then again, I have like thirty to go T_T
Answer #10
Looks like Gimpy is faster than me
Just have very VERY little to do right now
Answer #11
Well it now 00:09 I’have little to do right now like you but have a brain like ass
Answer #12
David spent 5 hours on a trip into the country and back. He walked in at the rate of 2 mph and waked out at the rate of 3 mph. How far, in miles, into the country did he go?
Thanks =O
I would ask my parents for help, but sadly they can’t really speak english that well.
Answer #13
Well the answer is I need to sleep and 6 (2 . x = 3 . (5-x) ==> x = 3 is the time for going in and 2 . 3 = 6 is the distance) You need more practice =)
Answer #14
Formula is distance = velocity x time btw
Answer #15
Damn, beaten to that one. Girlfriend was checking her e-mails.
Put differently. If he walks x miles in the country then he takes x/2 hours going in and x/3 hours coming out (because time = distance/speed).
These two added together must equal 5 so (x/2)+(x/3)=5
Multiply through by 2 then 3:
3x+2x=5*2*3
add:
5x=5*6
divide:
x=6 miles