Here you go I hope I helped
Answer: 0.3439
Step-by-step explanation:
Given :The last four digits for telephone numbers are randomly selected (with replacement).
Here , each position can be occupied with any of the digit independently .
Total digits = 10
Total digits other than 0 = 9
For each digits , the probability that it is not 0 =
If we select 4 digits , The probability of getting no 0 =
(By multiplication rule of independent events)
Now , the probability that for one such phone number, the last four digits include at least one 0. = 1- P(none of them is 0)
=1- 0.6561=0.3439
Hence, the probability that for one such phone number, the last four digits include at least one 0. is 0.3439 .
Answer:
-3+i
Step-by-step explanation:
Collect like terms
-2-1=-3
+3i-2i=i
-3+i
This follows from the half-angle identity for cosine.