Mathematics Stack Exchange is a question and answer site for people studying math at any level and professionals in related fields. Join them; it only takes a minute:

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

For instance if given values are $f(1.1) = 1$, $f(1.9) = 2$, $f(2.7) = 3$, $f(3.5) = 4$, $f(4.3) = 5$ and ever increasing by $0.8$ for each number, if I were to enter a value of $1.5$ the answer is $1.5$ but if I enter $2.3$ the answer is $2.5$ what is a formula that would express this?

share|cite|improve this question
sorry i did not understand question,is it about rounding number? – dato datuashvili Mar 29 '13 at 20:28
i think you can search about ceil and floor function – dato datuashvili Mar 29 '13 at 20:29
no not rounding its a specific gravity problem at a reading of 0 I get 0 at 1oz per gallon I get sg of 1.1 at 2oz per gallon I get 1.9sg at 3oz per gallon I get 2.7sg, the sg goes up by .8 from this point on, I need a formula so I can calculate the oz per gallon from any specific gravity reading. – user70070 Mar 29 '13 at 20:40
up vote 1 down vote accepted

Your required formula should be $$f(x)=\frac{x-0.3}{0.8}$$

share|cite|improve this answer
Thank you Vincent great work. much appreciated works like a charm. – user70070 Mar 30 '13 at 0:20

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.