Answer:
18 units
Step-by-step explanation:
Answer:
The 95% confidence interval for the true mean speed of thunderstorms is [10.712, 13.688].
Step-by-step explanation:
Given information:
Sample size = 10
Sample mean = 12.2 mph
Standard deviation = 2.4
Confidence interval = 95%
At confidence interval 95% then z-score is 1.96.
The 95% confidence interval for the true mean speed of thunderstorms is
Where, 
is sample mean, z* is z score at 95% confidence interval, s is standard deviation of sample and n is sample size.
![CI=[12.2-1.488, 12.2+1.488]](https://tex.z-dn.net/?f=CI%3D%5B12.2-1.488%2C%2012.2%2B1.488%5D)
![CI=[10.712, 13.688]](https://tex.z-dn.net/?f=CI%3D%5B10.712%2C%2013.688%5D)
Therefore the 95% confidence interval for the true mean speed of thunderstorms is [10.712, 13.688].
She took a total of 60 minutes
she answered both mulitiple choice and extended response in the total time which is 60 minutes
she took 2 minutes on rach multiple choice question and 6 minutes for the extended response
let x=number of multiple choice questions
let y=number of extended response questions
we can deduce that
total time =x*2+y*6
60=2x+6y
also we can deduce
20=x+y
since 20 ia the sum of multiple choice and extended response
for part 2 we just solve the system of equations
60=2x+6y
20=x +y
lets multiply the second equation by 2 so we can get rid of x
60=2x+6y
40=2x+2y
subtracting the two equations from each other to yields
20=0 +4y
y=5
to get x we substitute in one of the equations we derived from question 1
x+y=20
substituting y for its value we get
x+5=20
x=15
