maths problem

lol, I remember doing this like 3 years ago

2000 = 275 x 10^(0.018t)

You have final = initial (Then all the other crap...)and that's all you really need to know.

For one that's asking for the half life of something it's practically the same way...

Say you want to find what 100g of an element will be in 6 years if the half life is every six months.

There are twelve 6-month periods in six years so you would have

Final = Initial(1/2)^12

Where the final is what your looking for, the initial is 100g (what you start with), the 1/2 is the half-life, and the 12 is the periods...

All these problems are somewhat of teh same...

I'm going to major in math so if you guys need any help :D lolz

-Q
 
What chapter is that problem in? I need it so I can find it easier.
it was in some practice paper we were given.
what im confused at is wether to use Ihusers method or logs?
oh and @captain, ive got a few papers to go through so im sure this thread will come in handy :p ... oh and +1
 
it is definatly logarithms.

edit-
you will first get: log[base 10](2000/255)=.018t
then: 0.89448=.018t
then finally: t=49.69387
(gotta love windows calculator...)
it should be 47.8
i tried your method and i get the same answer as you :confused:
 
the way wood is doing it is correct. Thats what i get with my graphing calculator too. you should be fine.
 
how come the answer booklet says 47.8? is it a typo or has it some how being rounded very differently lol?
ive done some other questions today but ive spotted some tough ones which i might post later.
 
It's always possible that it is a typo. I"m sorry to say that i got that one marked wrong... :(

lol i had 200 sumthing
 
It's always possible that it is a typo. I"m sorry to say that i got that one marked wrong... :(

lol i had 200 sumthing
how did you manage that. its pretty obvious it cant be 200 as that would give a pretty big number, well bigger than 200 anyway :)
lol, anyway ill get some more qu's up tonight. you can all suffer my pain
 
a new problem:

67qw5ed.jpg


oh and if anyone could clarify the right method for the first question that would be great. wood's way looks right but why is it a different answer? it is just a typo on my answer sheet then?
 
These are weird probs.
integration of that, wouldn't it just be 5lg x - 2lg x? Well, no, never mind.

I don't really understand the concept of the problem. Never heard of the trapeze rule either.
 
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