$\begin{gathered} \text{Let;s assume the sp}e\text{d of boat in still water is x.} \\ And\text{ the spe}ed\text{ of stream is y.} \\ For\text{ upstream,} \\ (x-y)\times8=456 \\ x-y=57\ldots(1)_{} \\ (x+y)\times9=783 \\ x+y=87 \\ x=87-y\ldots(2) \\ \text{Now, substitute the value of x in the equation (1).} \\ 87-y-y=57 \\ -2y=57-87 \\ 2y=30 \\ y=15\text{ km/hours (rate of current)} \\ \text{Substitute the value of y in the equation (2).} \\ x=87-15 \\ x=72\text{ km/hours (boat in still water)} \end{gathered}$

4 0

1 year ago

A crane lifts an air conditioner weighing 800 Newtons up to the roof of a building in New York City. It took one minute to raise

tia_tia [17]

Answer:

160,000 Nm

2667 Nm/sec

Step-by-step explanation:

Work = weight * distance

= 800 * 200

= 160,000 Nm

Power = rate of work done

= 160,000 / 60

= 2667 Nm/sec

4 0

3 years ago

You choose two different songs on a music playlist at random. Out of 80 songs on the playlist, 36 are hip hop songs. The first s

dexar [7]

Answer:

35/79

Step-by-step explanation:

Assuming you can't choose the same song a second time, the probability is 35/79.

If you can choose the same song, the probability is 36/80, which reduces to 9/20.

7 0

4 years ago

Why is 1/3 greater than 1/6

Korvikt [17]

Because 1/3 is equal to 2/6 which is greater than 1/6

3 0

3 years ago

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