AccelePrep for the ACT Test 2nd Edition Student Text

C HAPTER 5 | H YPER P REP M ATH • 99

One of the most powerful common-sense test-taking strategies that is available to you is using the given units to check your solution. Now, how many times have you solved a problem by multiplying when you should have divided or by dividing when you should have multiplied? Yes, we are all guilty. But a really slick way of avoiding the mistake is to put the units into the solution. Let’s start with a simple example. 8. The EPA highway mileage estimate for a certain vehicle is 32 miles per gallon of gasoline. If the estimate is correct, how far, in miles, will the vehicle travel on 8 gallons of gasoline? F. 4 G. 24 H. 40 Ǥ ʹͷͲ K. 256 Now let’s look at a more complicated example. 9. What is the total cost of 3.5 pounds of asparagus at $2.80 per pound and 3.5 pounds of leeks at $2.66 per pound? A. $1.86 6. Researchers have determined that 12 out of every 50 persons in a population have genetic marker EXL, which triggers an allergic dermatological reaction in response to contact with the leaves of Toxicodendron vernix . In a population of 1,500 persons of similar genetic make-up, approximately how many can be expected to have EXL? F. 36 G. 40 H. 125 Ǥ ͵͸Ͳ K. 750 7. •™‹‹‰ ’‘‘Ž ™‹–Š ƒ…ƒ’ƒ…‹–› ‘ˆ ʹͷǡͲͲͲ ‰ƒŽŽ‘• ‹• „‡‹‰ ϐ‹ŽŽ‡† „› ƒ ™ƒ–‡” ’‹’‡ –Šƒ– ϐŽ‘™• ƒ– ƒ…‘•–ƒ– ”ƒ–‡Ǥ – ͻǣͲͲ ƒǤǤǡ –Š‡ ’‘‘Ž…‘–ƒ‹• 5,500 gallons, and at 1:00 p.m. the pool contains 17,500 gallons. If no ™ƒ–‡” ‹• †”ƒ‹‡† ˆ”‘ –Š‡ ’‘‘Žǡ ƒ– ™Šƒ– –‹‡ ™‹ŽŽ –Š‡ ’‘‘Ž „‡ ϐ‹ŽŽ‡† –‘ capacity? A. 2:30 p.m. B. 3:30 p.m. C. 4:00 p.m. D. 7:00 p.m. E. 8:40 p.m.

Examples:

STRATEGY ALERT Use your units to check your math or even solve a problem.

USING UNITS TO CHECK SOLUTIONS

Example:

Example:

B. $2.57 C. $9.31 D. $9.80 E. $19.11