Q11. 
An anti aircraft gun can take a maximum of four shots at an enemy plane moving away from it. The probability of hitting the plane at the first, second, third and fourth shots are 0.4, 0.3, 0.2 and 0.1 respectively. What is the probability that the plane is hit when all the four shots are fired? 
A.  0.6872 

B.  0.4379 

C.  0.6976 

D.  None of these 
Q12. 
An experiment succeeds twice as often as it fails. What is the probability that in the next 5 trials there will be four successes? 
A.  $0$ 

B.  $\left(\frac{2}{3}\right)^4$ 

C.  $5\times \left(\frac{2}{3}\right)^4\times \left(\frac{1}{3}\right)$ 

D.  $ \left(\frac{2}{3}\right)^4\times \left(\frac{1}{3}\right)$ 
Q13. 
Dinesh speaks truth in 3/4 cases and Abhishek lies in 1/5 cases. What is the percentage of cases in which both Dinesh and Abhishek contradict each other in stating a fact? 
A.  60% 

B.  35% 

C.  20% 

D.  15% 
Q14. 
When 3 fair coins are tossed together, what is the probability of getting atleast 2 tails? 
A.  1/4 

B.  2/3 

C.  1/3 

D.  1/2 
Q15. 
$x_1,x_2,x_3,x_4.......x_{50}$ are are fifty real numbers such that $x_r The probability that the five numbers have $x_{20}$ as the middle is: 
A.  $\dfrac{^{20}C_2\times ^{30}C_2}{^{50}C_5}$ 

B.  $\dfrac{^{19}C_2\times ^{30}C_2}{^{50}C_5}$ 

C.  $\dfrac{^{19}C_2\times ^{31}C_2}{^{50}C_5}$ 

D.  None of these 