Important Rates You Should Know for the ASVAB
Remembering a few important rates will go a long way when you take the ASVAB. A rate is a fixed quantity — a 5% interest rate, for example. It can mean the speed at which one works (John reads at the rate of one page per minute). Or it can mean an amount of money paid based on another amount (life insurance may be purchased at a rate of $1 per $100 of coverage). A rate is often a speed, something per a unit of time.
Word problems often ask you to solve problems that involve speed or simple interest rates. Here are two rate formulas you should commit to memory:
- Simple interest: I=Prt, where I represents the amount of interest, P is the principal (the initial amount invested), r is the interest rate, and t is the length of time the money is invested.
- Distance: d=rt , where d represents the distance traveled, r is the rate (speed) of travel, and t is the amount of time traveled.
In a rate, you can generally think of the word per as a division sign. For instance, suppose someone drives 141 miles in 3 hours, and you have to find the average speed. You want the rate of speed in miles per hour, so you take miles (distance) divided by hours (time): 141 miles ÷ 3 hours = 47 miles/hour. Using algebra, you can rearrange the distance formula to say the same thing: d ÷ t = r.