Answer
Find out the speed of the boat in still water .
To proof
Let us assume that the speed of the boat in still water be u .
As given
The speed of a stream is 4 mph
hence
speed upstream = u - 4
speed downstream = u + 4
Formula
As given
A boat travels 8 miles upstream in the same time it takes to travel 16 miles downstream.
First case for the upstream
Second case for the downstream
now compare the equations
simplify the equation
8( u +4 ) = 16 (u -4)
8u +32 = 16u - 64
8u = 96
u = 12 mph is the speed of the boat in still water .
Hence proved
The speed of the stream = 4 mph.
Let us assume speed of the boat in still water = x mph.
Total speed upstream = (x-4) mph.
Total speed downstream = (x+4) mph.
We know, time, speed and distance relation.
Time = Distance / Speed.
Total time taken upstream = 8 / (x-4)
Total time taken downstream = 16/(x+4).
Time taken upstream = time taken downstream.
Therefore,
8 / (x-4) = 16/(x+4).
On cross multiplication, we get
16(x-4) = 8(x+4).
16x - 64 = 8x +32.
Adding 64 on both sides, we get
16x - 64+64 = 8x +32+64
16x = 8x + 96.
Subtracting 8x from both sides, we get
16x-8x = 8x-8x + 96.
8x = 96.
Dividing both sides by 8, we get
x = 12.
Answer
Answer:
Answer is z= 43/36
Step-by-step explanation:
We have given,
2 13/18 - z = 1 19/36
Since 2 13/18 = 49/18 and 1 19/36 = 55/36
So we can write,
2 13/18 - z = 1 19/36
or 49/18 - z = 55/36
or 49/18 - 55/36 = z
or (98 -55)/36 = z
or 43/36 = z
Hence we got z = 43/36
A) variance = 222.7, standard deviation = 49,595.9
B) variance = 49,595.9, standard deviation = 24,798
C) variance = 49,595.9, standard deviation = 222.7
D) variance = 57,861.9, standard deviation = 240.5
Answer:
Part 1) variance = 49,595.9
Part 2) standard deviation = 222.7
Option C
Step-by-step explanation:
we have
set of data
step 1
Find the mean
Adds the values and divide by the number of values
In this problem the number of values is 7
step 2
for each number: subtract the Mean and square the result
step 3
work out the mean of those squared differences
----> this value is called the "Variance"
step 4
The standard deviation is the square root of the variance
so
The standard deviation is equal to
Answer:
The probability that a coin flip is a head or a tail is 0.5. The probability that a coin flip is either a head or a tail is 1. The probability that a three-coin-flip is two heads and a head or a tail is 0.25.
Step-by-step explanation: