Answer:
The mean life time of the bulbs is approximately 739 hours
Step-by-step explanation:
Here, we want to calculate the mean life time
From the question, 95% of the bulbs die before 920 hours
What this mean is that the probability that a bulb will die before 920 hours is 95% = 95/100 = 0.95
Now, we need the z-score that is exactly equal to this value
Using the standard normal distribution table, the z-score corresponding to this probability value is 1.645
Mathematically;
z-score = (x-mean)/SD
In this case, x is 920, SD is standard deviation which is 920 hours
thus, we have it that;
1.645 = (920-mean)/110
110(1.645) = 920 - mean
180.95 = 920 - mean
mean = 920- 180.95
mean = 739.05
Answer:
53 adults
Step-by-step explanation:
Let
x---------> the number of adults
y -------> the number of students
we know that

-----> equation A
-----> equation B
Equate equation A and equation B
solve for x
therefore
There are 53 adults
Answer:
k = -10/7 and k = -3
Step-by-step explanation:
Given: <em>y</em> = <em>kx</em> + 2
where k is the slope of line and 2 is y-intercept.
∵ line <em>y</em> = <em>kx </em>+ 2 is passing through point <em>P</em> (-7, 12), ∴ <em>x</em> = -7 and <em>y </em>= 12
Now substituting the value of x and y in above equation,
<em>y </em>= <em>kx</em> + 2
12 =<em> k</em>(-7) + 2
-7<em>k</em> = 12 - 2
- 7<em>k</em> = 10

In the same way, ∵ line <em>y</em> = <em>kx </em>+ 2 is passing through point <em>P</em> (3, -7), ∴ <em>x</em> = 3 and <em>y </em>= -7
<em>y </em>= <em>kx</em> + 2
Now substituting the value of x and y in above equation,
-7 =<em> k</em>(3) + 2
<em>3k</em> = -7 - 2
<em>3k</em> = - 9
<em>k</em> = -3
Answer:
19.4
Step-by-step explanation:
Perimeter = 53 feet
P = 2L + 2H
L = 7.1 feet
2L + 2W = 53 feet
2*7.1 + 2w = 53
14.2 + 2w = 53
2W = 53 - 14.2
2W = 38.8
W = 38.8/2
W = 19.4
H = 19.4