Answer:
B. 0.4
Step-by-step explanation:
Use the definition of the probability

You have to find the probability that a randomly selected reference book is hard cover. Hence, from the table
- Number of all possible outcomes = Number of Reference books = 25
- Number of all favorable outcomes = Number of Hardcover Reference books = 10
So, the probability is

From all those aforementioned, the true statement is: Thanh’s grade is 2.5 standard deviations below the mean of the test grades.
Answer:
21
Step-by-step explanation:
4a-2=a+4
+2 to both sides
4a=a+6
-a from both sides
3a=6
Answer:Step-by-step explanation:
10