Question

На одной мельнице могут перемолотить 15 т.. пшеницы за 60 ч, а на другой - 30ч. За сколько часов перемолотят 15т пшеницы обе мельницы, если будут работать вместе???

Answer 1

1)  15:60=0,25(т/ч)-делает первая мельница
2)  30:15=0,5(т/ч)-делает вторая
3)   15:(0,25+0,5)=20(ч)-потребуется работать мельницам вместе

Answer 2

Problem Analysis

We have two mills, one of which can grind 15 tons of wheat in 60 hours, and the other can grind 15 tons of wheat in 30 hours. We need to determine how many hours it will take for both mills to grind 15 tons of wheat if they work together.

Solution

To solve this problem, we can calculate the combined grinding rate of both mills and then use it to find the time required to grind 15 tons of wheat.

Let's calculate the grinding rate of each mill first: - Mill 1: 15 tons of wheat in 60 hours, so the grinding rate is 15 tons / 60 hours = 0.25 tons per hour. - Mill 2: 15 tons of wheat in 30 hours, so the grinding rate is 15 tons / 30 hours = 0.5 tons per hour.

Now, let's calculate the combined grinding rate of both mills: - Combined grinding rate = Grinding rate of Mill 1 + Grinding rate of Mill 2 = 0.25 tons per hour + 0.5 tons per hour = 0.75 tons per hour.

Finally, we can calculate the time required to grind 15 tons of wheat using the combined grinding rate: - Time = Amount of wheat / Combined grinding rate = 15 tons / 0.75 tons per hour = 20 hours.

Therefore, if both mills work together, it will take them 20 hours to grind 15 tons of wheat.

Answer

If both mills work together, it will take them 20 hours to grind 15 tons of wheat.

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