Answer:
And rounded up we have that n=421
Step-by-step explanation:
We know that the sample proportion have the following distribution:

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by
and
. And the critical value would be given by:
The margin of error for the proportion interval is given by this formula:
(a)
And on this case we have that
and we are interested in order to find the value of n, if we solve n from equation (a) we got:
(b)
We assume that a prior estimation for p would be
since we don't have any other info provided. And replacing into equation (b) the values from part a we got:
And rounded up we have that n=421
Answer: the number of new light bulbs that they put in is 36
Step-by-step explanation:
The Marino's put new light bulbs in all the fixtures the new house.
Each fixture used 2 light bulbs and each room had 3 fixtures. This means that the number of bulbs in each room would be 3×2 = 6 bulbs.
The new house had 6 rooms. This means that the total number of bulbs in 6 rooms would be
6 × 6 = 36 bulbs
If you want to solve it in standard way,follow:
9x=63 ==> x=7
Answer:
x = 27
Step-by-step explanation:
∠ ABD and ∠ BDE are alternate angles and are congruent, then
∠ BDE = 72°
∠ ADB + ∠ BDE + ∠ EDF = 180° ( sum of angles on a straight line ), that is
2x + 72 + 2x = 180
4x + 72 = 180 ( subtract 72 from both sides )
4x = 108 ( divide both sides by 4 )
x = 27