Answer:
a) Probability(6,7,8,9)=0.0024
b) Probability(6,7,8,8)=0.0012
c)Probability (7,7,8,8)=0.0006
d)Probability (7,8,8,8)= 0.0004
Step-by-step explanation:Permutation is given by the equation =n!/(n-r)!
P=4!/(4-4)!=4×3×2×1=24
Each digit has 10 possible ways
Total number of ways=10×10×10×10=10,000
a) Probability (6,7 8,9)=24/10,000=0.0024
b) 6,7,8,8. 6 and 7 occured once but 8 occured twice
Using multinominal coefficient =4!/(1!2!)=24/2=12
Possible ways for6,7,8,8 =10,000
Probability (6,7,8,8)=12/10,000= 0.0012
c) 7,7 8,8. 7 and 8 occured twice. Usining multinominal Coefficient=4!/(2!2!)=24/4=6
Possible ways for 7,7,8,8=10,000
Probability (7,7,8,8)=6/10,000=0.0006
d) 7,8,8,8,. 7 occured once while 8 occured three times. Using multinominal coefficient =4!/(1!3!)=24/6=4
Possible ways for7,8,8,8 =10,000
Probability (7,8,8,8)=4/10000=0.0004
