Given:
Sample mean = 65.4
Standard deviation = 1.2
Sample size = 45
Confidence level = 99%
To find:
The confidence interval.
Solution:
The formula for confidence interval is
where, 
is sample mean, z* is confidence value, s is standard deviation and n is sample size.
Confidence value or z-value at 99% = 2.58
Putting the given in the above formula, we get
Therefore, the correct option is D.
31 students do their homework every night
Answer:
$14.8
Step-by-step explanation:
There is a mistype in the question. It should say: ... <em>si cada uno de ellos hicieron una contribución de </em><em>dieciseis</em><em> pesos...</em>
So if everybody contributes $14, they make a total of 14*x, where x denotes the number of students. In this scenario, $4 are left, calling y to the cost of the trip, then:
14*x = y - 4 (eq. 1)
In the other scenario, everybody contributes $16 and $6 are in excess, so
16*x = y + 6 (eq. 2)
subtracting eq. 1 to eq. 2:
16*x - 14*x = y + 6 - (y - 4)
2*x = y + 6 - y + 4
2*x = 10
x = 10/2 = 5
Replacing this value in eq. 1:
14*5 = y - 4
70 + 4 = y
y = $74
If every student pays: 74/5 = $14.8, then they would get altogether the exact cost of the trip
Yes because all sides would be equal to 5 which would give you 5*4 = 20 units.
Call the price of the bike before mark up 'x', then we have:
x + 0.25x = 210
1.25x = 210
x = 168
Therefore, the bike cost $168 before 25% price increase.
