Hints on review problems

Here are hints or answers for selected problems from today's review problem set.

• 1a. Hint: P(G|D)=130/250
  
• 1b. Hint: P(D|G)=130/273
  
• 1c. Hint: P(D and G)=130/525
  
• 2. Find 1 - P(contains no 8's) = 1 - (# FDN's with no 8's)/(total # FDN's).
  
• 3. Need to multiply three probabilities.
  
• 4. Don't overlook that the fives and nonfives can occur in 4C2=6 different orders, so the answer needs to include a multiplication by 6.
  
• 5. Think of inclusion of each bill as a yes/no decision.
  
• 6a. Find (# 3-letter words made from oca)/(# 3-letter words made from ocean).
  
• 6b. Find (# 3-letter words made from ouai)/(# 3-letter words made from mountains). Don't overlook that mountains includes a double letter.
  
• 7f. Answer is 1/5.
  
• 7g. Answer is 1.