Question

Помогите решить задачу: Треть пути мотоциклист ехал со скоростью 85км\ч.Затем он снизил скорость на 15км\ч.За сколько часов проехал мотоциклист остальной путь, если всего он проехал 420км ?

Answer 1

1. 420:3=140 км -  1/3 части.
2. 85-15=70 км/ч - U велосипедиста на остальном участке.
3. 420-140=280 км  - остальной путь.
4. 280:70=4 ч
Ответ : за 4 часа  проехал мотоциклист остальной путь.

Answer 2

1) 420÷3=140(км)проехал мотоцикл со скоростью 85км/ч.
2) 85-15=70(км/ч)скорость такой скоростью он двигался после снижения скорости
3) 140×2=280(км) мотоцикл проехал со скоростью 70км/ч
4) 280÷70=4(ч)за столько времени он проехал оставшийся путь
Ответ:за 4 часа.

Answer 3

Problem Analysis

We are given that a motorcyclist initially traveled at a speed of 85 km/h and then reduced their speed by 15 km/h. We need to determine how many hours it took for the motorcyclist to cover the remaining distance, given that the total distance traveled was 420 km.

Solution

To solve this problem, we can follow these steps:

1. Calculate the distance covered at the initial speed of 85 km/h. 2. Calculate the remaining distance after reducing the speed by 15 km/h. 3. Determine the time taken to cover the remaining distance.

Let's calculate each step in detail.

Step 1: Distance covered at the initial speed of 85 km/h

To calculate the distance covered at the initial speed of 85 km/h, we can use the formula:

Distance = Speed × Time

Let's denote the time taken at the initial speed as t1.

The distance covered at the initial speed can be calculated as:

Distance1 = Speed1 × t1

Substituting the given values:

Distance1 = 85 km/h × t1

Step 2: Remaining distance after reducing the speed by 15 km/h

To calculate the remaining distance, we need to subtract the distance covered at the initial speed from the total distance.

Let's denote the remaining distance as Distance2.

Distance2 = Total Distance - Distance1

Substituting the given values:

Distance2 = 420 km - (85 km/h × t1)

Step 3: Time taken to cover the remaining distance

To calculate the time taken to cover the remaining distance, we can use the formula:

Time = Distance / Speed

Let's denote the time taken to cover the remaining distance as t2.

The time taken to cover the remaining distance can be calculated as:

t2 = Distance2 / Speed2

Substituting the given values:

t2 = (420 km - (85 km/h × t1)) / (85 km/h - 15 km/h)

Now, we have an equation with two variables, t1 and t2. We need to solve this equation to find the values of t1 and t2.

Let's solve this equation step by step.

1. Simplify the equation:

t2 = (420 km - 85 km/h × t1) / 70 km/h

2. Multiply both sides of the equation by 70 km/h:

70 km/h × t2 = 420 km - 85 km/h × t1

3. Rearrange the equation:

85 km/h × t1 + 70 km/h × t2 = 420 km

4. We can rewrite the equation as:

85t1 + 70t2 = 420

Now, we have a system of linear equations. We can solve this system to find the values of t1 and t2.

However, since we don't have enough information to solve the system, we cannot determine the exact values of t1 and t2. We need additional information, such as the relationship between t1 and t2, to solve the system.

Therefore, without additional information, we cannot determine the time taken to cover the remaining distance.

Please let me know if there is anything else I can help you with.