Answer: 287.1 billion liters
Explanation:
Water usage per person: 30 liters/day
World population: 9.57 * 10^9
Total water needed = Water usage per person * World population
Total water needed = 30 liters/day * 9.57 * 10^9
To simplify the calculation, we can express 9.57 * 10^9 in scientific notation:
Total water needed ≈ 30 liters/day * 9.57 * 10^9
To multiply the two values, we multiply the numbers and add the exponents:
Total water needed ≈ (30 * 9.57) * 10^(0 + 9)
Total water needed ≈ 287.1 * 10^9
Now, we can convert the result back to standard notation:
Total water needed ≈ 287,100,000,000 liters
Therefore, if every person in the world used 30 liters of water a day, the total amount of water needed for one day would be approximately 287.1 billion liters.