Question

Аша помогая бабушке на даче прополола три одинаковые грядки с клубникой.На первую и вторую грядки Маша потратила 58 мин а на первую и третью 48мин. За какое время были прополоты все три грядки если третью грядку Маша пропалывала с той же скоростью как первую и вторую в среднем?

Answer 1

Так как на прополку 1-й и 2-й грядки Маша затратила 58 мин, то на прополку третьей грядки она затратила t₃ = 58:2 = 29 (мин.)

Тогда на прополку 1-й грядки ушло времени: t₁ = 48 - 29 = 19 (мин.),
а на прополку 2-й грядки: t₂ = 58 - 19 = 39 (мин.)

Таким образом, t₁+t₂+t₃ = 19+39+29 = 87 (мин.) = 1 ч 27 мин

Ответ: все три грядки были прополоты за 1 ч 27 мин.

Answer 2

58-48=10 мин     это   разница между второй и третьей грядками 
58:2=29 мин        это третья грядка (по условию задачи среднее между первой и второй)    
48-29=19 мин   потратила на первую грядку  
29+10=39 мин   это на вторую грядку

Answer 3

Solution:

To solve this problem, we can use a system of equations to represent the time it takes Masha to weed each row and then solve for the total time.

Let's denote: - x as the time it takes Masha to weed the first row, - y as the time it takes Masha to weed the second row, and - z as the time it takes Masha to weed the third row.

We are given the following information: 1. Masha spent 58 minutes weeding the first and second rows. 2. Masha spent 48 minutes weeding the first and third rows.

We can express this information as the following system of equations: 1. x + y = 58 (equation 1) 2. x + z = 48 (equation 2)

To find the time it takes Masha to weed all three rows, we need to solve for x, y, and z.

Let's solve the system of equations to find the values of x, y, and z.

Solving the System of Equations:

From equation 1: x = 58 - y (equation 3)

Substitute equation 3 into equation 2: (58 - y) + z = 48

Simplify: z = 48 - 58 + y z = -10 + y (equation 4)

Now we have expressions for x and z in terms of y.

To find the time it takes Masha to weed all three rows, we need to find the value of y.

We know that Masha spends the same average time on each row, so we can find the average time and use it to solve for y.

The average time is given by: (x + y + z) / 3

Substitute the expressions for x and z: ((58 - y) + y + (-10 + y)) / 3 (48 - 10) / 3 38 / 3 12.67

So, the average time Masha spends on each row is 12.67 minutes.

Now, we can find the time it takes Masha to weed all three rows by substituting the average time into one of the original equations. Let's use equation 1:

x + y = 58 58 - y + y = 58 58 = 58

This equation is true for any value of y, which means there are infinitely many solutions. Therefore, the time it takes Masha to weed all three rows is 58 minutes.

So, Masha spent 58 minutes weeding all three rows.