Answer:
Mean is 81%
standard deviation is approximately 4.2%
Step-by-step explanation:
Since the number of boys equals the number of girls, but it is not given, we name it "N". and proceed to calculate the mean as:
Mean = (0.78 * N + 0.84 * N) /(2 N)
using that the total number of students must be N boys + N girls = 2 N
Then the Mean becomes: N *(0.78 + 0.84) /(2 N) = (0.78 + 0.84) / 2 = 1.62 / 2 = 0.81
So the mean is 81%
Now, standard deviation will be calculated by first adding the squares of the deviations: (X-0.81)^2 for the N boys and for the N girls, and then finding the square root of this and finally dividing by the square root of N. That is:
Now finding the square root of this value, and finally dividing it by the square root of N:
which in percent form is: approximately 4.2%
Answer:
median =55
Step-by-step explanation:
The median is the middle number. It will fall exactly between those two numbers. Take the average
(51+59)/2 = 110/2 =55
Newton's Law of Cooling
Tf=Ts+(Ti-Ts)e^(-kt) where Tf is temp at time t, Ts is temp of surroundings, Ti is temp of object/fluid. So we need to find k first.
200=68+(210-68)e^(-10k)
132=142e^(-10k)
132/142=e^(-10k)
ln(132/142)=-10k
k=-ln(132/142)/10
k≈0.0073 so
T(t)=68+142e^(-0.0073t) so how long until it reaches 180°?
180=68+142e^(-0.0073t)
112=142e^(-0.0073t)
112/142=e^(-0.0073t)
ln(112/142)=-0.0073t
t= -ln(112/142)/(0.0073)
t≈32.51 minutes
Answer:
The probability that he teleports at least once a day = 
Step-by-step explanation:
Given -
Evan lives in Stormwind City and works as an engineer in the city of ironforge in the morning he has three Transportation options teleport ride a dragon or walk to work and in the evening he has the same three choices for his trip home.
Total no of outcomes = 3
P( He not choose teleport in the morning ) = 
P( He not choose teleport in the evening ) =
P ( he choose teleports at least once a day ) = 1 - P ( he not choose teleports in a day )
= 1 - P( He not choose teleport in the morning ) 
P( He not choose teleport in the evening )
= 
= 
