Answer:
Step-bLet X be the number of calls received by an office on Monday morning between 8:00 AM and 9:00 AM.
In mathematical terms,
X
∼
P
o
i
s
s
o
n
(
2
)
.
The PMF of the random variable X is given as,
P
(
X
=
x
)
=
e
−
2
×
2
x
x
!
f
o
r
x
=
0
,
1
,
2
,
.
.
.
.
.
=
0
E
l
s
e
w
h
e
r
e
The probability of getting no more than 3 calls between eight and nine in the morning is obtained by the following way,
P
(
X
≤
3
)
=
P
(
X
=
0
)
+
P
(
X
=
1
)
+
P
(
X
=
2
)
+
P
(
X
=
3
)
=
e
−
2
×
2
0
0
!
+
e
−
2
×
2
1
1
!
+
e
−
2
×
2
2
2
!
+
e
−
2
×
2
3
3
!
=
0
.13534
+
0
.27067
+
0
.27067
+
0
.18045
=
0
.85712
Hence the probability of getting no more than 3 calls between eight and nine in the morning is 0.85712.y-step explanation: