Answer:
140
Step-by-step explanation:
When working HCF and LCM problems, I like to think in terms of this little diagram:
(a [ b ) c]
It shows me one of the numbers is ab, the other is bc, the HCF is b and the LCM is abc. "a" and "c" must be relatively prime for "b" to be the HCF.
__
Here, we're given ...
b = 20
ab = 320
abc = 2240
Then ...
c = abc/(ab) = 2240/320 = 7
x = bc = 20(7) . . . . . . equivalently, x = (abc·b)/(ab) = (2240·20)/320
x = 140
Answer:
ST = 12 units
Step-by-step explanation:
As RA is parallel to ET, the angle in R is equal to the angle in T, and the angle in A is equal to the angle in E, so the triangle RAS is similar to the triangle SET.
If RT is 21 units, we have that RS + ST = 21 -> RS = 21 - ST
Using a rule of three with the sides of the triangle (as they are proportional), we have:
RS / ST = AR / ET
(21 - ST) / ST = 6 / 8
4 * (21 - ST) = 3*ST
84 - 4*ST = 3*ST
7*ST = 84
ST = 12 units
Answer:
The best estimate of the number of times out of 39 that Ariana is on time to class is 27.
Step-by-step explanation:
For each class, there are only two possible outcomes. Either Ariana is on time, or she is not. The probability of Ariana being on time for a class is independent of other classes. So we use the binomial probability distribution to solve this question.
Binomial probability distribution
Probability of exactly x sucesses on n repeated trials, with p probability.
The expected value of the binomial distribution is:

The probability that Ariana is on time for a given class is 69 percent.
This means that 
If there are 39 classes during the semester, what is the best estimate of the number of times out of 39 that Ariana is on time to class
This is E(X) when n = 39. So

Rounding
The best estimate of the number of times out of 39 that Ariana is on time to class is 27.
Answer:
6 times
Step-by-step explanation:
Turn that fraction into a decimal. 3/4=0.75
Divide!
4.5/0.75=6