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soldi70 [24.7K]
3 years ago
11

A motorboat covers the distance from one pier to the other pier in 4 hours and the way back in 5 hours. What is the speed of the

boat in still water, if it covers 70 km with the current in 3.5 hours?
(its not 20 i tried)
Mathematics
1 answer:
aleksklad [387]3 years ago
3 0
R = speed in still water
r + c = speed with current
r - c = speed against current

3.5(r + c) = 70
r + c = 20
c = 20 - r

4(r + c) = distance from pier to pier
5(r - c) = distance from pier to pier
4(r + c) = 5(r - c)
4(r + 20 - r) = 5(r - 20 + r)
80 = 10r - 100
180 = 10r
18 = r
The speed in still water is 18 km/hour
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Step-by-step explanation:

To find out Mean the formula is : total sum of data set / number of values

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Mean = 8

Now for variance we will form a table

x                  11     11     3      1      11      11

(x - Mean)    3     3    -5     -7      3      3  

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2 years ago
Read 2 more answers
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Volgvan

Answer:

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Step-by-step explanation:

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b) The sequence of natural numbers which are multiplied by 3 and added to 1 is represented by the function f(n) = 3\cdot n + 1, n\in \mathbb{N}. Let see the first five elements of the sequence: 4, 7, 10, 13, 16,...

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