Probability help

[Whofan101]

Can I please have some help with these 2 questions.

1. A survey of 400 people found that 104 people liked coffee, 245 liked tea, and 39 liked both. What is the probability that a person likes both beverages?
Round your answer to three decimals.

2. A multiple-choice test has 6 questions, each with 3 possible answers. What is the probability that a test taker answers all the questions correctly? Round your answer to three decimals.

 

[Dr.Peterson]

We can help, but we'd like to know where you need help with these. That's why we ask you to show your own thinking:

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The first question is about the basic definition of probability. If 39 people like both, out of a total of 400 people, what is the probability that a randomly chosen person from that population likes both?

The second seems to ask you to assume a person guesses answers randomly and independently. (Why would a teacher make such an assumption??) What is the probability of getting the first question right under those conditions? How about the second? How would you combine the probabilities for all 6 questions?

 

[JJPBadAtMafs]

For the first part of the question, it might also be helpful to draw a Venn Diagram, that might be one way I might go about it, however, as stated above there are other methods too!