For proof of 3 divisibility, abc is a divisible by 3 if the sum of abc (a + b + c) is a multiple of 3.
<h3>
Integers divisible by 3</h3>
The proof for divisibility of 3 implies that an integer is divisible by 3 if the sum of the digits is a multiple of 3.
<h3>Proof for the divisibility</h3>
111 = 1 + 1 + 1 = 3 (the sum is multiple of 3 = 3 x 1) (111/3 = 37)
222 = 2 + 2 + 2 = 6 (the sum is multiple of 3 = 3 x 2) (222/3 = 74)
213 = 2 + 1 + 3 = 6 ( (the sum is multiple of 3 = 3 x 2) (213/3 = 71)
27 = 2 + 7 = 9 (the sum is multiple of 3 = 3 x 3) (27/3 = 9)
Thus, abc is a divisible by 3 if the sum of abc (a + b + c) is a multiple of 3.
Learn more about divisibility here: brainly.com/question/9462805
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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:
7
Step-by-step explanation:
Fiction books: (1/6) of 30 books = 5 books
Non-fiction books: (3/5) of (30) books = 18 books
The subtotal here is 5 + 18, or 23.
23 of the books are either fiction or non fiction.
30 - 23, or 7, of the books remain (are neither fiction nor non-fiction).
A) set x as the number of cameras
18x=9x+1800
9x=1800
x=200
b) i'm assuming it's increasing production from my answer in a, so the profit would be 18(250)-(9*250+1800)=4500-4050=450