Answer:
a) 0.6915; b) 2.83 years
Step-by-step explanation:
For part a,
The formula for a z score is
Our mean, μ, is 3.25 and our standard deviation, σ, is 0.5.
This gives us
z = (3-3.25)/0.5 = -0.25/0.5 = -0.5
Using a z table, we see that the area under the curve to the left of this is 0.3085. However we want the area to the right; this means we subtract from 1:
1-0.3085 = 0.6915
For part b,
We look in the cells of a z table to find the value closest to 20%, or 0.2000. This is 0.2005, which corresponds with a z score of -0.84:
-0.84 = (X-3.25)/0.5
Multiply both sides by 0.5:
0.5(-0.84) = ((X-3.25)/0.5)(0.5)
-0.42 = X-3.25
Add 3.25 to each side:
-0.42+3.25 = X-3.25+3.25
X = 2.83
The advertised life would be 2.83 years.
Answer: x=5
Step-by-step explanation:
Answer:
Step-by-step explanation:
download an app called connects go to the app store and look up geometry and scroll down its blue and has a figure 8 on it
25+N=61.
N= 36
So there is 36 numbers in Abby's cell phone.
Answer: 90% confidence interval is; ( - 0.0516, 0.3752 )
Step-by-step explanation:
Given the data in the question;
n1 = 72, n2 = 17
P1 = 54 / 72 = 0.75
P2 = 10 / 17 = 0.5882
so
P_good = 0.75
P_bad = 0.5882
standard ERRROR will be;
SE = √[(0.75×(1-0.75)/72) + (0.5882×(1-0.5882)/17)]
SE = √( 0.002604 + 0.01424)
SE = 0.12978
given confidence interval = 90%
significance level a = (1 - 90/100) = 0.1, |Z( 0.1/2=0.05)| = 1.645 { from standard normal table}
so
93% CI is;
(0.75 - 0.5882) - 1.645×0.12978 <P_good - P_bad< (0.75 - 0.5882) + 1.645×0.12978
⇒0.1618 - 0.2134 <P_good - P_bad< 0.1618 + 0.2134
⇒ - 0.0516 <P_good - P_bad< 0.3752
Therefore 90% confidence interval is; ( - 0.0516, 0.3752 )
