1. INTERNATIONAL UNIVERSITY OF BUSINESS AGRICULTURE AND TECHNOLOGY
Midterm examination STA 240
Full marks: 100 Time: 50 minutes
1. Two coins are tossed; find the probability that
a) At most one tail is obtained.
b) At least one head is obtained.
2. The number of persons X, in a family chosen at random has the following probability
distribution:
X 0 1 2 3 4
P(X) 0.1 0 m 0.2 0.3
a) Find the value of m.
b) Find the average family size E (X).
c) Also find V(X).
3. Interpret the following results :
a) r = 0.79 b) r = 0.65 c) r = 0.34 d) r = 0.18
4. A die is tossed 3 times. What is the probability of
a) No fives turning up? b) 3 fives? c) 1 five?
5. Vehicles pass through a junction on a busy road at an average rate of 300 per hour.
a. Find the probability that none passes in a given minute.
b. What is the expected number passing in two minutes?
c. Find the probability that this expected number actually pass through in a given two-
minute period.
6. Find the following probabilities:
a. P (Z > 1.06)
b. P (Z < -2.15)
c. P (1.06 < Z < 4.00)
7. p(x)=x ; 0<x<1
A) Find E (X).
B) Also find V(X).
Md. Mortuza Ahmmed