Answer:
it is b
Step-by-step explanation:
Using the linear regression equation, the concentration of the unknown solution is 0.2161 M.
Linear regression describes the relationship of two variables. It may not be exact but it is the line that best fit the data. The equation for a linear regression is in the form y = bx + a, where x and y are the two variables.
If the absorbance of an unknown was determined to be 0.67 absorbance units, using the linear regression equation provided from the plot, substitute the value of absorbance to the variable y and solve for the value of x or the concentration.
y = 3.8674x - 0.1657
0.67 = 3.8674x - 0.1657
3.8674x = 0.67 + 0.1657
3.8674x = 0.8357
x = 0.2161
Hence, the concentration is 0.2161 M.
Learn more about linear regression here: brainly.com/question/25311696
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Answer:
It is very cool that Mariana wears her winter coat when the temperature is colder than -4 degrees Celsius
that means when it is 10 degrees Celsius, she won't wear her winter coat
Step-by-step explanation:
Let the numbers are 4x and 7x. According to the question if each number is increased by 20, the ratio becomes 7 : 9.
Then,
( 4x + 20 ) : ( 7x + 20 ) = 7 : 9
9( 4x + 20 ) = 7( 7x + 20 )
9( 4x ) + 9( 20 ) = 7( 7x ) + 7( 20 )
9( 20 ) - 7( 20 ) = 7( 7x ) - 9( 4x )
2( 20 ) = 49x - 36x
40 = 13 x
40 / 13 = x
Therefore, number are :–
4 x = 4( 40 / 13 ) = 160 / 13
7 x = 7( 40 / 13 ) = 280 / 13