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## Statistics Assignment

1. A pet store owner is interested in the number of pets owned by her customers. She takes a random sample of 100 customers and asks them: “How many pets do you own?” (a) What is an appropriate method for graphing the data? (b) Why is it appropriate?

2. Choose the best answer. Justify for full credit.

(a) A marketing agent asked people to rank the quality of a new soap on a scale from 1 (poor) to 5 (excellent). The level of this measurement is: (i) interval (ii) nominal (iii) ordinal (iv) ratio

(b) A STAT 200 instructor surveyed nearly 100 students, who took STAT 200 in Fall 2018, and asked how many hours they spent on STAT 200 each week. The average hours spent was 12.25 hours. The value 12.25 is a: (i) parameter (ii) statistic (iii) population (iv) sample 3. The frequency distribution below shows the distribution of average seasonal rainfall in San Francisco, as measured in inches, for the years 1967-2017. (Show all work. Just the answer, without supporting work, will receive no credit.) STAT 200: Introduction to Statistics Final Examination, Spring 2019 OL4 3

(a) Why is it appropriate to use a grouped frequency distribution for this data?

(b) Complete the frequency table with frequency and cumulative relative frequency. Express the cumulative relative frequency to two decimal places. (c) What percentage of season in this sample has a seasonal rainfall between 0 and 19.99 inches, inclusive?

(d) Which of the following seasonal rainfall groups does the median of this distribution belong to? 10- 19.99, 20 – 29.99, or 30 – 39.99?

Why? 4. A school district wanted to assess the effectiveness of a new reading readiness program for 1st graders. The school district is divided into the individual first-grade classrooms and 10 classrooms are randomly selected. All of the children in each of the 10 selected classrooms are assessed.

(a) What type of sampling method is being used?

(b) Please explain your answer. 5. A study was conducted to determine whether the mean braking distance of four-cylinder cars is greater than the mean braking distance of six-cylinder cars.