The response time of a re department in an emergency call is the period between
the time the call is received by the dispatcher and the time the rst truck service
arrives on the scene. It was found that the response time follows a normal
distribution with mean of 12 min and standard deviation of 2 min.
given - mean M
=
12
SD
=
2
=
0
a) P(x = 10)
z=
10
12
=
=
=
- 1p(z7
-
1)
=
1
-
p(z)
-
1)
1
=
-
0
.
1587
=
0 8413
.
-
8
z=
P(z(1)
=
-
12
0 8413
.
=
=
-
P(z 2)
=
2
0 228
.
z
=
0
.
8413
fi
b)
=
-
= > P(212(1)
-
0 0228
.
=
0 8185
.