(a) Average time to get to school
Average time (minutes) = Summation of the two means = mean time to walk to bus stop + mean time for the bust to get to school = 8+20 = 28 minutes
(b) Standard deviation of the whole trip to school
Standard deviation for the whole trip = Sqrt (Summation of variances)
Variance = Standard deviation ^2
Therefore,
Standard deviation for the whole trip = Sqrt (2^2+4^2) = Sqrt (20) = 4.47 minutes
(c) Probability that it will take more than 30 minutes to get to school
P(x>30) = 1-P(x=30)
Z(x=30) = (mean-30)/SD = (28-30)/4.47 ≈ -0.45
Now, P(x=30) = P(Z=-0.45) = 0.3264
Therefore,
P(X>30) = 1-P(X=30) = 1-0.3264 = 0.6736 = 67.36%
With actual average time to walk to the bus stop being 10 minutes;
(d) Average time to get to school
Actual average time to get to school = 10+20 = 30 minutes
(e) Standard deviation to get to school
Actual standard deviation = Previous standard deviation = 4.47 minutes. This is due to the fact that there are no changes with individual standard deviations.
(f) Probability that it will take more than 30 minutes to get to school
Z(x=30) = (mean - 30)/Sd = (30-30)/4.47 = 0/4.47 = 0
From Z table, P(x=30) = 0.5
And therefore, P(x>30) = 1- P(X=30) = 1- P(Z=0.0) = 1-0.5 = 0.5 = 50%
Probability of getting heads: 1/2
Probability to get 2 heads out of three tries is: 1/8
Work: 1/2 x 1/2 x 1/2 = 1/8
2x^4
13b-10
5y+10
5a^3
2b^2+8a
Answer:
=−66k4+12188
Step-by-step explanation:
Answer:
an infinite number of solutions
Step-by-step explanation:
−3x −17 = −17 −3x
left side = right side TRUE because -3x-17 is the same as -17-3x
we can rearrange the the equation
−3x −17 +17 = −17 +17−3x, add 17 on both sides of the equations
-3x = -3x, divide both sides by (-3)
x = x
Since this equation is <u>always true ( for any number ) </u>we have <u>an infinite number of solutions</u> (since there are is an infinity of numbers.)
