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A motorboat travels 168 kilometers in 4 hours going upstream. It travels 280 kilometers going downstream in the same amount of t

Grace [21]

Answer:

The speed of the boat is 56 km/hr

The rate of the current is 14 km/hr

Step-by-step explanation:

We are given the following;

Distance traveled upstream = 168 km
Time taken to travel upstream = 4 hours
Distance traveled down stream = 280 km
Time taken down stream = 4 hours

We are required to determine the speed of the boat in still water and the speed of the current.

We are going to take;

Speed of the boat as = x km/hr

Rate of flow of current = y km/hr

We can determine the speed of the boat upstream;

Speed = Distance ÷ time

= 168 km ÷ 4 hours

= 42 km/hr

But, the speed upstream is given by (x - y) km/hr

Therefore; ( x-y) km/hr = 42 km/hr ......................... Eqn 1

Speed of the boat down stream

speed = 280 km ÷ 4 hours

= 70 km/hr

But, the speed downstream is given by (x+y) km/hr

Therefore, x+y km/hr = 70 km/hr ........................... Eqn 2

Solving Eqn 1 and Eqn 2 simultaneously;

x - y = 42

x + y = 70

Eliminating x

-2y = - 28

y = 14 km/hr

Solving for x,

x = 42 + y

= 42 + 14

= 56 km/hr

Therefore, the speed of the boat is 56 km/hr while the rate of the current is 14 km/hr

8 0

4 years ago

which expression represents purely real numbers and which expression represents non-real complex number?

Ray Of Light [21]

Incomplete question. However, I provided some explanation about non-real complex numbers.

Explanation:

In Mathematics, the term complex numbers (non-real complex numbers) in simple terms refers to numbers that containing an imaginary addition to it.

For example, the numbers 3i, 3 + 5i, 3i/4 are non-real numbers because of the addition of an imaginary part which is denoted by 'i'.

While real numbers, on the other hand, are numbers that do not include an imaginary part; they stand on their own, such as whole numbers 0, 1, 2, 3, etc, rational numbers like 3/4, etc.

5 0

3 years ago

Lucy spends 4 hours a week babysitting. Her sister Lily spends seven eighths as much time babysitting. Does Lily babysit for mor

olganol [36]

Answer:

Lily babysit for less than 4 hours.

Step-by-step explanation:

Given:

Lucy spends in a week babysitting for 4 hours.

Lily spends seven-eighths of 4 hours.

Now, to find whether Lily babysit for more than 4 hours or less than that.

Number of hours Lucy babysit = 4 hours.