Answer:
840
Step-by-step explanation:
120 is 40% of 300, and 840 is 40% of 2100 is 840.
Hello!
First you have to find what the temperature was at the 3 stages
It started at 87
Then went down 10
87 - 10 = 77
Then up 17
77 + 17 = 94
Then you take the difference from the current temperature from the lowest temperature
94 - 77 = 17
The answer is D
Hope this helps!
Average speed is given by [Total Distance] ÷ [Total Time]
Average speed =

km/hour
So the mean is 72.97
We need to subtract the mean from each value and square it.
(65-72.97)^2= 63.5209
(68-72.97)^2=24.7009
(69-72.97)^2=15.7609
(70-72.97)^2=8.8209
(71-72.97)^2= 3.8809
(72-72.97)^2=0.9409
(90-72.97)^2=290.0209
(95-72.97)^2=485.3209
Now we add up the new values ( also consider their frequency) and find their mean.
Add the values
63.5209+(2 •24.7009=49.4018)+(5•15.7609=78.8045)+(8•8.8209=70.5672)+(7•3.8809=27.1663)+(3•0.9409=2.8227)+(2•290.0209=580.0418)+(2•485.3209=970.6418)= 1,842.967
Divide by total numburs to find the mean
1,842.967/ 30=61.43223333
The standar deviation is the square root of the mean so is
Square root of 61.43223333=7.837871735
Round to the nearest tenth
Standard Deviation is 7.8