SCHOOL OF LIBERAL ARTS AND HUMAN SERVICES STAT 120 Fundamental of Statistics

1 | P a g e M r . B M a u r i c e
College of Science, Technology
and Applied Arts of Trinidad and Tobago

SCHOOL OF LIBERAL ARTS AND HUMAN SERVICES
STAT 120 Fundamental of Statistics
Assignment # 2 (5%)
Semester 2
Year 2019/20
Hilda and seven (7) friends (of course I was one of the friends) attended all four games
of T20 cricket games between Pakistan and the West Indies in 2017. As her
contribution, she had to purchase eight sandwiches for each of the games on the
morning of each match.
(a) The first game was held on Saturday 25th March 2017 in Barbados. She went to
the Massy (in Hastings) to get the sandwiches. The manager had informed her
that the store has two types of sandwiches, chicken and cheese (sandwiches are
not labeled). He said that past experience had shown that the probability of a
customer getting a cheese sandwich is independently 0.3. She selected eight
sandwiches at random and paid for them.
(i) Determine the probability that the number of cheese sandwiches she
bought was:
(i) Exactly two (ii) More than 1
(iii) Between 4 and 7 [6]
(ii) How many chicken sandwiches does she expect to have bought? [2]
2 | P a g e M r . B M a u r i c e
(b) The last three games were held in Trinidad. She went to the Massy Store (on
French Street) to get the sandwiches. Massy Stores via a news release has
informed the public that the store has two types of sandwiches, chicken and
cheese (sandwiches are labeled). They went on to state that past experience had
shown that the probability of a customer getting a cheese sandwich is
independently 0.4.
(i) On Thursday 30th March 2017 (late for the game) Hilda ran into the store
and randomly selected eight sandwiches from those on display, pays and
leaves the store.
Does a binomial distribution provide an appropriate model for the number
of cheese sandwiches Hilda carried to cricket that day? Briefly state why.
[5]
(ii) Two of her friends do not eat chicken (the other six people in the group
have no preference). When she went to the store on Saturday 1st April
2017, Hilda decided to ensure that there were exactly two cheese
sandwiches. If having selected eight sandwiches at random she finds that
they do not include two cheese sandwiches, she replaces the appropriate
number of chicken sandwiches with cheese sandwiches.
Does a binomial distribution provide an appropriate model for the number
of cheese sandwiches Hilda carried to cricket that day? Briefly state why.
[2]
(c) On Sunday 2nd April 2017, Hilda again bought eight sandwiches. This time
there were four (4) cheese and four (4) chicken sandwiches. The first four
friends to eat a sandwich that day, have no preference on the type of
sandwich available. Each selected one of the available sandwiches at
random and ate it.
Does a binomial distribution provide an appropriate model for the number
of cheese sandwiches eaten by her friends? Briefly state why. [3]