A recruit runs 3 miles in 27 minutes at a steady pace. At the same pace, how long will it take to run 5 miles?
45 minutes First find the time for one mile: 27 ÷ 3 = 9 minutes per mile. Then multiply by 5 miles: 9 × 5 = 45 minutes.
A jacket normally costs $40. It’s on sale for 25% off. What is the sale price?
$30 25% of $40 is $10, because 0.25 × 40 = 10. Take that off the normal price: $40 − $10 = $30.
On four quizzes, Dana scored 82, 90, 76 and 88. What score does she need on the fifth quiz to have an average of exactly 85 for all five?
89 An average of 85 over five quizzes means a total of 5 × 85 = 425 points. Her first four add up to 82 + 90 + 76 + 88 = 336. She needs 425 − 336 = 89.
Candid most nearly means:
frank Candid means open and honest, saying what you really think. Frank means the same thing.
The sergeant gave a terse answer and walked away.
Terse most nearly means:
brief Terse means using very few words. A terse answer is short and to the point. The sentence backs this up: the sergeant answered and walked away.
Diligent most nearly means:
hardworking Diligent means showing steady care and effort in your work. Hardworking is the closest match.
Many people wait until they feel thirsty before they drink water. By then, the body may already be short of fluid. In hot weather or during hard exercise, a person can lose more than a liter of sweat in an hour. Drinking small amounts of water regularly, before thirst sets in, helps the body stay cool and keeps performance from dropping.
What is the main idea of the passage?
It’s better to drink water regularly than to wait until you feel thirsty. The passage builds one point: thirst comes late, so you should drink small amounts regularly. The facts about sweat support that advice.
The town library changed its schedule last spring. On weekdays it now opens at 8 a.m., two hours earlier than before, and closes at 9 p.m. Weekend hours did not change.
Before the change, what time did the library open on weekdays?
10 a.m. It now opens at 8 a.m., which is two hours earlier than before. So before the change it opened two hours later: 10 a.m.
If 3x − 7 = 14, what is x?
7 Add 7 to both sides: 3x = 21. Then divide both sides by 3: x = 7. Check: 3 × 7 − 7 = 21 − 7 = 14.
A circle has a radius of 4 inches. Using π ≈ 3.14, what is its area?
50.24 square inches The area of a circle is πr². Here that’s 3.14 × 4 × 4 = 3.14 × 16 = 50.24 square inches.
Multiply: (x + 3)(x − 5)
x² − 2x − 15 Multiply each term in the first bracket by each term in the second: x·x = x², x·(−5) = −5x, 3·x = 3x, and 3·(−5) = −15. The middle terms combine: −5x + 3x = −2x. So the result is x² − 2x − 15.
Which part of a plant cell carries out photosynthesis?
Chloroplast Chloroplasts contain chlorophyll, the green pigment that captures light energy. They use it to turn carbon dioxide and water into sugar, giving off oxygen.
At sea level, pure water boils at:
100°C At sea-level air pressure, pure water boils at 100°C, which is 212°F. It freezes at 0°C, which is 32°F.
Which planet is closest to the Sun?
Mercury Mercury is the closest planet to the Sun. The order going outward starts Mercury, Venus, Earth, Mars.
A 12-volt battery is connected to a single 4-ohm resistor. How much current flows through the circuit?
3 amperes Ohm’s law says current equals voltage divided by resistance (I = V ÷ R). So I = 12 ÷ 4 = 3 amperes.
Which of these materials is the best conductor of electricity?
Copper Metals such as copper let electric current flow easily, which is why most household wiring is copper. Rubber, glass and dry wood are insulators.
In a gasoline engine, which part makes the spark that ignites the fuel and air in the cylinder?
Spark plug The spark plug sits in the cylinder head. The ignition system sends it a high-voltage pulse, and it jumps a gap as a spark that ignites the compressed fuel-air mixture.
Which tool would you use to check that a shelf is perfectly horizontal?
Level A level has a small vial of liquid with an air bubble. When the bubble sits centered between the lines, the surface is level, meaning horizontal.
A 60-pound box sits on a lever 2 feet from the fulcrum. How much force must you push down with at a point 6 feet from the fulcrum, on the other side, to balance it? Ignore the weight of the lever.
20 pounds A lever balances when weight × distance is the same on both sides. The load side is 60 × 2 = 120. So the force × 6 must also equal 120, and 120 ÷ 6 = 20 pounds.
A gear with 20 teeth turns at 60 revolutions per minute (rpm). It meshes with a gear that has 40 teeth. How fast does the larger gear turn?
30 rpm Meshed gears pass the same number of teeth per minute. The small gear moves 20 × 60 = 1,200 teeth a minute. The large gear has 40 teeth, so it turns 1,200 ÷ 40 = 30 times a minute.