<span>The sum of two numbers is 48.
a + b = 48
;
If one third of one number is 5 greater than one sixth of another number,
a = b + 5
multiply both sides by 6, cancel the fractions
2a = b + 30
2a - b = 30
</span><span>use elimination to solve this
a + b = 48
2a - b =30
-------------Addition eliminates b, find a
3a = 78
a =
a = 26
then
26 + b = 48
b = 48 - 26
b = 22</span>
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
Answer:
In a certain Algebra 2 class of 30 students, 22 of them play basketball and 18 of them play baseball. There are 3 students who play neither sport. What is the probability that a student chosen randomly from the class plays both basketball and baseball?
I know how to calculate the probability of students play both basketball and baseball which is 1330 because 22+18+3=43 and 43−30 will give you the number of students plays both sports.
But how would you find the probability using the formula P(A∩B)=P(A)×p(B)?
Thank you for all of the help.
That formula only works if events A (play basketball) and B (play baseball) are independent, but they are not in this case, since out of the 18 players that play baseball, 13 play basketball, and hence P(A|B)=1318<2230=P(A) (in other words: one who plays basketball is less likely to play basketball as well in comparison to someone who does not play baseball, i.e. playing baseball and playing basketball are negatively (or inversely) correlated)
So: the two events are not independent, and so that formula doesn't work.
Fortunately, a formula that does work (always!) is:
P(A∪B)=P(A)+P(B)−P(A∩B)
Hence:
P(A∩B)=P(A)+P(B)−P(A∪B)=2230+1830−2730=1330
