14 Finance The number of FTSE 100 company share prices that went up from the previous day were recorded for 50 days. Number of share prices that went up Frequency 1–20 7 21–40 12 41–60 18 61–80 10 81–100 3 Q14 Literacy hint The largest 100 companies on the London stock market are called the FTSE 100. Each day, their share prices can go up, down or stay the same. a Estimate the probability that on the next day i 21 to 40 share prices will go up ii more than 60 share prices will go up. b The London stock exchange trades for 357 days in a year. On how many days would you expect fewer than 21 share prices to rise? c Estimate the probability that fewer than 21 share prices will rise on each of two consecutive days. 15 Draw a tree diagram to show the probability of picking a milk, dark or white chocolate at random from this box, eating it, then picking another chocolate at random. Work out the probability of a two white chocolates b at least one milk chocolate. 16 Reasoning Umeka placed some red and blue counters in a bag. She drew this tree diagram to show the probabilities of taking two counters from the bag at random, one at a time. 1st pick 2nd pick Red 5 9 Red 1 2 Blue Red Blue Q17 hint a Was the first counter replaced in the bag before the second counter was taken? Explain your answer. b Copy and complete the tree diagram. 1st game win 17 Last season, a football club won 20 games, drew 8 games and lost 10 games. Use a tree diagram to estimate the probability that the club will a win the next three games b win two of the next three games. 18 Reflect Write a probability question where the answer is 0.6 for each of these types of probability: • mutually exclusive events • independent events • experimental probability Compare your three questions with others in your class. draw lose Q18 hint Look back at the lessons where you learned about these types of probability. You could use a game or a sports match as the context. Reflect Blue Unit 8 Probability 198