The probability that he is in the right job is 0.65, so the probability he is in the wrong job is 0.35, and similarly, the probability that the test is inaccurate is 0.3. Thus, the probability that someone is in the right job and the test is then wrong is 0.65*0.3=.195, and the probability that someone is in the wrong job and the test is wrong is 0.35*.3=.105.
Let x equal Thomas' age. Then Huilan's age is 2x. Set up an equation to model this situation:
x+2x=78
<em>*Combine like terms*</em>
3x=78
<em>*Divide both sides by 3*</em>
x=26
Hope this helps!!