The modal class is 70 - 80 and the mean speed is 66.4
<h3>How to determine the modal class?</h3>
The table of values is given as:
Speed Frequency
40 - 50 10
50 - 60 16
60 - 70 19
70 - 80 23
80 - 90 12
The modal class is the class with the highest frequency
The class 70 - 80 has the highest frequency of 23
Hence, the modal class is 70 - 80
<h3>How to determine the mean?</h3>
Rewrite the frequency table to include the class midpoints
x f
45 10
55 16
65 19
75 23
85 12
The estimate of the mean speed is then calculated as:
So, we have:
Evaluate
Hence, the mean speed is 66.4
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Answer:
28
Step-by-step explanation:
2x + 7 = 4x - 7
14 = 2x
x = 7
BC = 4x = 4(7) = 28
<span>Assuming the reaction is of 1st order, we can
start using the formula for rate of 1st order reaction:</span>
dN / dt = k * N
Rearranging,
dN / N = k dt
Where N = amount of sample, k = rate constant, t = time
Integrating the equation from N = Ni to Nf and t = ti to
tf will result in:
ln (Nf / Ni) = k (tf – ti)
Since k is constant, we can equate to situations.
Situation 1 is triple in size every days, situation 2 is after 20 days.
ln (Nf / Ni) / (tf – ti) = k
ln (3Ni / Ni) / 4 = ln (Nf / 40) / 20
Calculating for Nf,
<span>Nf =
9,720 bacteria </span>
Answer : 32
( angles of a triangle add up to 180)