Предмет: Математика, автор: Nastenka453867

Помогите пожалуйста. Через первую трубу бассейн можно наполнить за 20 ч, а через вторую за 30 ч. За сколько часов наполнится бассейн при совместной работе этих труб?

Ответы

Автор ответа: Sleeplessness1

0

1 - объем работы

1/20 скорость 1 трубы

1/30 - скорость второй трубы

1/20 + 1/30 = 3/60 + 2/60 = 5/60 = 1/12

1 : 1/12 = 1 * 12 = 12 ч

Ответ: за 12 часов

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