1.
Musa's aquarium has 8 tanks, and each tank holds 7 clownfish. At feeding time, 12 of the clownfish hide in the coral. How many clownfish can Musa still see?
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Answer:
Did you know? A clownfish lives inside a stinging sea anemone. A slimy coat on its skin keeps it from being stung.
2.
Idris collects 54 seashells on the beach. He gives 6 of them to his little sister, then arranges the rest equally into 8 rows on a shelf. How many shells are in each row?
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Answer:
Did you know? A seashell is really a skeleton — the animal grows it on the outside instead of the inside, and it never takes it off.
3.
A turtle rescue center starts the month caring for 315 sea turtles. It releases 148 of them back into the ocean, then takes in 96 more that were found hurt. How many turtles are at the center now?
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Answer:
Did you know? A female sea turtle usually returns to lay her eggs on the very same beach where she hatched, even decades later.
4.
A whale-watching boat leaves the dock at 9:40 a.m. It sails out for 50 minutes, watches whales for 35 minutes, then sails back for 50 minutes. What time does it get back to the dock?
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Answer:
Did you know? A blue whale's heart is about the size of a small car, and its call can travel for hundreds of miles underwater.
5.
A diving club packs 50 air tanks into crates for a trip. Each crate holds exactly 6 tanks. How many crates can be filled completely, and how many tanks are left over?
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Answer:
Did you know? The word SCUBA is short for "Self-Contained Underwater Breathing Apparatus" — the tank lets a diver carry air along.
1.
A research ship unloads 18 crates of shark tagging kits, and each crate holds 32 kits. The kits are shared equally among 12 dive teams. How many kits does each team get?
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Answer:
Did you know? Scientists clip small tags to sharks to track them. One great white named Nicole swam from South Africa to Australia and back — about 12,000 miles.
2.
Yusuf saves $12 every week for 15 weeks to go to a diving camp. The camp costs $135 and a snorkel set costs $28. How much money does he have left?
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Answer:
Did you know? Water blocks red light first, so about 30 feet down everything looks blue-green — a diver's red glove turns gray.
3.
A rectangular tide-pool exhibit measures 45 feet long and 16 feet wide. What is its area? If one bag of sand covers 45 square feet, how many bags are needed to cover the whole floor?
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Answer:
Did you know? Tide-pool animals get covered by the sea and then left in the open air twice a day, so they have to survive both.
4.
A reef tank is divided into 20 equal sections for planting new coral. Five volunteers each plant 3 sections. What fraction of the tank did they plant in all, and what fraction is still empty? Write both fractions in simplest form.
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Answer:
Did you know? Coral reefs cover less than 1% of the ocean floor, but about 25% of all ocean species live on them.
5.
A beach cleanup crew collects 1,850 pieces of plastic each day for 6 days. Their goal for the whole month is 15,000 pieces. How many pieces did they collect, and how many more do they need to reach the goal?
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Answer:
Did you know? A plastic bottle can take about 450 years to break apart in the ocean — longer than the United States has existed.
3rd Grade
1. 44 clownfish.
8 tanks × 7 fish = 56. Then 56 − 12 hiding = 44.
2. 6 shells per row.
54 − 6 to his sister = 48. Then 48 ÷ 8 rows = 6.
3. 263 turtles.
315 − 148 released = 167. Then 167 + 96 new = 263.
4. 11:55 a.m.
50 + 35 + 50 = 135 minutes = 2 hr 15 min. Then 9:40 a.m. + 2 hr 15 min = 11:55 a.m.
5. 8 full crates, 2 tanks left over.
50 ÷ 6 = 8 remainder 2. 8 crates full, 2 tanks left (they'd need a 9th crate).
4th Grade
1. 48 kits per team.
18 crates × 32 kits = 576. Then 576 ÷ 12 teams = 48.
2. $17 left.
$12 × 15 weeks = $180 saved. Then $180 − $135 − $28 = $17.
3. Area = 720 sq ft; 16 bags of sand.
45 × 16 = 720 square feet. Then 720 ÷ 45 = 16 bags.
4. Planted 15/20 = 3/4; empty 5/20 = 1/4.
5 volunteers × 3 sections = 15 planted. 15/20 simplifies to 3/4. Empty: 20 − 15 = 5, so 5/20 = 1/4.
5. 11,100 pieces collected; 3,900 more needed.
1,850 × 6 days = 11,100. Then 15,000 − 11,100 = 3,900 to go.