Question

6 классПо плану опытная машинистка набирает рукопись статьи за 12 часов. Через 2,5 часа после начала работы к ней присоединилась практикантка, и совместно они закончили набор на 3часа раньше запланированного срока. Сколько часов понадобилось бы на набор рукописи практикантке?

Answer 1

 Пусть за х часов выполняет работу практикантка. Тогда за 1 час машинистка набирает 1/12 часть рукописи, а практикантка 1/х часть рукописи за 1 час. Сначала 2,5 часа работала машинистка, т.е. выполнила 2,5/12 часть работы; потом 6,5 часов работала как машинистка, так и практикантка. Вся работа равна 1. 

                                            Составим уравнение:

2,5/12+6,5/12+6,5/х=1

9/12+6,5/х=1

6,5/х=1-9/12

6,5/х=1/4

 

 6,5=1/4х

х=6,5/0,25

х=26 (часов) понадобится практикантке.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Answer 2

Problem Analysis

To solve this problem, we need to determine how many hours the intern would need to complete the manuscript if she worked alone. We know that the experienced typist takes 12 hours to complete the manuscript, and after 2.5 hours of work, the intern joins her. Together, they finish the typing 3 hours earlier than planned.

Solution

Let's break down the problem step by step:

1. The experienced typist takes 12 hours to complete the manuscript. 2. After 2.5 hours of work, the intern joins her. 3. Together, they finish the typing 3 hours earlier than planned.

To find out how many hours the intern would need to complete the manuscript alone, we can subtract the time they worked together from the total time taken by the experienced typist.

Let's calculate the time they worked together: - The experienced typist worked for 12 hours. - The intern joined after 2.5 hours and they finished 3 hours earlier than planned. Therefore, they worked together for 12 - 2.5 - 3 = 6.5 hours.

Now, let's calculate the time the intern would need to complete the manuscript alone: - The experienced typist took 12 hours to complete the manuscript. - They worked together for 6.5 hours. - Therefore, the intern would need 12 - 6.5 = 5.5 hours to complete the manuscript alone.

So, the intern would need 5.5 hours to complete the manuscript alone.

Answer

The intern would need 5.5 hours to complete the manuscript alone.