math
posted by jay on .
I am taking a job related test consisting of several math sections. I have been out of school for quite some time and am looking to find the easiest place to get tips and tutorials to solve these questions. The topics are as follows: multiplication and division of fractions and mixed numbers, calculating percentages, calculating ratios and proportions, basic rules of probability, calculating rate problems using distance and time, calculating work rate problems, calculating averages, solving for unknown quantities, expressing word problems as equations. Any help would be greatly appreciated

For Calculating Percentages:
You can for example change 4.89 to .00489 % by moving the decimal two places.
or for science we usually divide the part of mass/ the whole and times it by 100 to get percentages.
Calculating ratios:
you can set up a proportion by..
x/30 = 1/3 and cross multiply and get 3x=30 and x=10.
Probability:
the probability of picking a green marble out of a total of 12 marbles in total and five of them are green would be 5/12.
Calculating Averages:
You would add all the sample of masses together and divide by how many there are. For example...you have an element with a mass of 16.00, 16.80,17.20 what is the average of the masses... you would add them up and divide by 3 since there is 3 masses. (you divide by the amount of samples)
Unknown Quantities:
you would solve for usually x or y and find your given values and determine what you are solving for and represent it with a variable.
For word problems:
It's more of a thinking type think. Common knowledge of figuring out an equation from the given information.