of 320 consumers polled, some purchase blu-ray movies, some only purchase movies on dvd, and some do both. if 300 people polled
purchase blu-ray discs and 280 purchase dvds and blu-ray discs, how many people only buy dvds? please help a. 300 b. 20 c. 280 d. 40
1 answer:
Answer:
20 people only buy dvds.
Step-by-step explanation:
There are two groups in this problem. One group of people that buys dvds and one that buys blu rays. The total amount of people who buy blu rays is 300, but there's an intersection between the groups and the size of this is 280 people who actually buy both. In order to find out how many people only buy DVDs we first need to figure out how many only buy blu-rays. That is:
people who only buy blu rays = people who buy blu rays - people who buys blu rays and dvds
people who only buy blu rays = 300 - 280 = 20
We can now calculate the amount of people who only buy dvds and that is:
people who only buy dvds =total amount of people - ( people who only buy blu rays + people who buy both)
people who only buy dvds = 320 - (20 + 280) = 320 - 300 = 20 people
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Answer with Step-by-step explanation:
We are given that
A and B are matrix.
A.We know that for two square matrix A and B
Then,
Therefore, it is true.
B. det A is the product of diagonal entries in A.
It is not true for all matrix.It is true for upper triangular matrix.
Hence, it is false.
C.
When is a factor of the characteristics polynomial of A then -5 is an eigenvalue of A not 5.
Hence, it is false.
D.An elementary row operation on A does not change the determinant.
It is true because when an elementary operation applied then the value of matrix A does not change.