OCR PURE — Question 11

Exam BoardOCR
ModulePURE
TopicDiscrete Probability Distributions
TypeVerify probability from independent trials

11 Alex models the number of goals that a local team will score in any match as follows.
Number of goals01234
More
than 4
Probability\(\frac { 3 } { 25 }\)\(\frac { 1 } { 5 }\)\(\frac { 8 } { 25 }\)\(\frac { 7 } { 25 }\)\(\frac { 2 } { 25 }\)0
The number of goals scored in any match is independent of the number of goals scored in any other match.
  1. Alex chooses 3 matches at random. Use the model to determine the probability of each of the following.
    1. The team will score a total of exactly 1 goal in the 3 matches.
    2. The numbers of goals scored in the first 2 of the 3 matches will be equal, but the number of goals scored in the 3rd match will be different. During the first 10 matches this season, the team scores a total of 31 goals.
  2. Without carrying out a formal test, explain briefly whether this casts doubt on the validity of Alex's model. \section*{END OF QUESTION PAPER}