If there are 1030 grains of sand on Playa de Sonrisa, how many of these grains of sand are submerged by the ocean at least once a day?

Question

Camryn Ford

Geography

20 September, 17:52

If there are 1030 grains of sand on Playa de Sonrisa, how many of these grains of sand are submerged by the ocean at least once a day?

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Answers (1)

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Missy · Answer 1

Answer: 85 percent

Explanation:

(1) 40% of the grains of sand are submerged at least twice a day - -> 0.4*1030 grains are submerged twice or more. Not sufficient,

(2) 55% of the grains of sand are not submerged exactly once a day. This imply that the remaining 45%, so 0.45*1030 grains, ARE submerged exactly once a day. Not sufficient.

(1) + (2) We have that 45% are submerged exactly once and 40% are submerged twice or more. Therefore, 45% + 40% = 85% are submerged at least once (once ore more). Sufficient.