A division problem is unsolved, so it is an unknown factor until ithe problem is solved.
ANSWER
C) 1, 3, 6, 10, 15, 21, 28, 36, 45
EXPLANATION
The recursive formula is,

when n is a natural number greater than 1.
When n=2,


when n=3,

when t=4,

When t=5,

when t=6,.

when t=7

When t=8,

When t=9,

Hence the first nine triangular number are
C) 1, 3, 6, 10, 15, 21, 28, 36, 45
Answer: a) 30, b) 0.2138, c) 0.0820
Step-by-step explanation:
Since we have given that
X be the number of calls in 1 hour = 60 minutes
Rate of one call every two minutes.

(a) What is the expected number of 911 calls in one hour?

(b) What is the probability of three 911 calls in five minutes? If required, round your answer to four decimal places.

Number of calls = 3
So, P(X=3) is given by

(c) What is the probability of no 911 calls during a five-minute period? If required, round your answer to four decimal places.

Hence, a) 30, b) 0.2138, c) 0.0820
Uhhh is this a real question because if it is I feel bad for the person who has to solve it lol
Answer:
the answer is of the question is 216