How much salt does 1 km3 of the Black Sea water contain if its average salinity is 21.8 ‰?

Let’s make the proportion:
1 km3 (1 ‰) – 1,000,000 tons of salts
1 km3 (21.8 ‰) – X t salts
X = 21.8 ‰ × 1,000,000 tons: 1 1 = 21,800,000 tons = 21.8 million tons
Answer: 1 km3 of the Black Sea water contains 21.8 million tons of salts.

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