Convert rates between units (e.g., mph to ft/s, per-hour to per-minute).
Free, timed SHSAT practice sets on rate conversion— every question includes a full worked explanation, and there's no account required.
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Convert a rate by multiplying by conversion fractions that equal 1, such as \(\tfrac{60 \text{ min}}{1 \text{ h}}\) or \(\tfrac{5280 \text{ ft}}{1 \text{ mi}}\). Set up each fraction so the unit you want to remove cancels.
Example: 60 miles per hour in feet per second: \(\dfrac{60 \text{ mi}}{1 \text{ h}} \times \dfrac{5280 \text{ ft}}{1 \text{ mi}} \times \dfrac{1 \text{ h}}{3600 \text{ s}} = \dfrac{60 \times 5280}{3600} = 88\) ft/s.
Quick rules:
Traps:
45 mph \(= 45 \times 5280 \div 3600 = 66\) ft/s. (Inverting the factor (\(45 \times 3600 \div 5280\)) gives about 30.68 ft/s. Using 100 minutes in an hour and 100 seconds in a minute (\(45 \times 5280 \div 10000\)) gives 23.76 ft/s. Dropping a zero from 3600 (\(45 \times 5280 \div 360\)) gives 660 ft/s.)
1 hour \(= 60\) minutes, so 2400 per hour \(\div 60 = 40\) per minute. (Dividing by 100, as if an hour had 100 minutes, gives 24 pages. Dividing by 24 instead of 60 gives 100 pages. Dropping a zero (dividing by 6 instead of 60) gives 400 pages.)
\(\$148 \times 5 = 740\) pesos. After spending: \(740 - 147 = 593\) pesos. (Forgetting to subtract the spending gives 740 pesos. Adding the 147 pesos instead of subtracting gives 887 pesos. Finding the dollars left instead (\(148 - 147 \div 5\)) gives 118.6 pesos.)