Question

All human blooid is one of the four types : O , A,B or AB. The distributions of the types varies a bit with race. If you choose an African American person at random , here is a table of the approcimate probabilities of that person having each of the different blood types.

Blood Types : O A B AB
0.5 ? 0.2 0.05

Using the table of probabilities above , the probability that the person chosen has blood type A is :
0.05
0.25
0.27
0.40
0.65

I'm having a bit of trouble with probability may someone walk me through it please, I'm willing to learn!

Answer 1

Your answer is 0.25

When dealing with probability, you know that the total must be equal to 1 when in decimals, or 100% when in percentages. This means that whatever the other 3 probabilities add up to, you must subtract that from 1 because you need what is left over as the total must be 1. 0.05 + 0.5 + 0.2 = 0.75, so 1 - 0.75 = 0.25

I hope this helps! I tried to explain but let me know if you still don't understand probability that well and I can help more :)