Answer:
0.80589
Step-by-step explanation:
So all of the numbers of correct answers less than 4 are 0,1,2,3
We need to calculate the probability for each separately and then add them together.
To find the probability we have to first find the combination. We know that there’s n=8 trials and that p=0.3. So 1-0.3 gives us 0.7.
The combination formula is: ! / (!(−)!)
So the n would always =8, and the r would be 0,1,2,3. So you would have to calculate it for 0,1,2,3 Separately. This can be done by hand or you can use a simple combinations calculator online.
For 0;
The combination is 1,
1 x 0.3^0 x 0.7^8-0 =
0.057648
For 1;
The combination is 8,
8 x 0.3^1 x 0.7^8-1 =
0.19765
For 2;
The combination is 28
28 x 0.3^2 x 0.7^8-2 =
0.296475
For 3;
The combination is 56
56 x 0.3^3 x 0.7^8-3 =
0.254122
All that’s left is to add these four numbers;
0.057647 + 0.19765 + 0.296475 + 0.254122 = 0.80589
