Question

Помогите решить задачу:Когда Петя учился во 2-ом классе ,скорость чтения была 45 слов/минуту. В четвёртом классе скорость чтения Пети 135 слов/минуту.За сколько часов смог бы прочитать четвероклассник Петя прочитать книгу которую во 2-ом классе он прочитал в течении 4 часов?

Answer 1

4 часа = 60 * 4 = 240 мин240 * 45 = 10800 слов Петя прочитал во втором классе за 4 часа10800 : 135 = 80 мин = 1 час 20 минПетя прочтёт книгу за 1 час 20 мин

Answer 2

Problem Analysis

To solve this problem, we need to find out how many hours it would take for Petya, a fourth-grade student, to read a book that he read in 4 hours when he was in the second grade. We are given that Petya's reading speed was 45 words per minute in the second grade and 135 words per minute in the fourth grade.

Solution

To find the number of words in the book, we need to know the reading time in the second grade and the reading speed in the fourth grade. We can then calculate the reading time in the fourth grade using the formula:

Reading Time = Number of Words / Reading Speed

Let's calculate the number of words in the book using the reading time in the second grade and the reading speed in the fourth grade.

Calculation

Given: - Reading speed in the second grade = 45 words per minute - Reading speed in the fourth grade = 135 words per minute - Reading time in the second grade = 4 hours

To calculate the number of words in the book, we need to convert the reading time in the second grade to minutes:

Reading time in the second grade = 4 hours * 60 minutes/hour = 240 minutes

Now, we can calculate the number of words in the book using the formula:

Number of Words = Reading Time * Reading Speed

Substituting the values:

Number of Words = 240 minutes * 45 words/minute = 10800 words

Now, we can calculate the reading time in the fourth grade using the formula:

Reading Time = Number of Words / Reading Speed

Substituting the values:

Reading Time = 10800 words / 135 words/minute = 80 minutes

To convert the reading time in the fourth grade to hours, we divide by 60:

Reading Time = 80 minutes / 60 minutes/hour = 1.33 hours

Therefore, it would take Petya approximately 1.33 hours to read the book that he read in 4 hours when he was in the second grade.

Answer

Petya would be able to read the book that he read in 4 hours when he was in the second grade in approximately 1.33 hours when he is in the fourth grade.

Please let me know if you need any further assistance!