Download 1. in a random sample of 50 vcrs, the mean repair cost was $75 and

1. IN A RANDOM SAMPLE OF 50 VCRS, THE MEAN REPAIR COST WAS $75 AND THE STANDARD
DEVIATION WAS $12.50. CONSTRUCT A 99% CONFIDENCE INTERVAL FOR THE POPULATION MEAN
COST.
2. A CHEESE PROCESSING COMPANY WANTS TO ESTIMATE THE MEAN CHOLESTEROL CONTENT
OF ONE SERVING OF ONE OF ITS PRODUCTS. THE ESTIMATE MUST BE WITHIN 0.5 MG OF THE
POPULATION MEAN. DETERMINE THE MINIMUM SAMPLE SIZE NEEDED TO CONSTRUCT A 95%
CONFIDENCE INTERVAL FOR THE POPULATION MEAN. ASSUME THE POPULATION STANDARD
DEVIATION IS 2.8 MG.
3. IN A RANDOM SAMPLE OF 12 ADULTS FROM THE US, THE MEAN WASTE RECYCLED PER PERSON
PER DAY WAS 1.4 POUNDS AND THE STANDARD DEVIATION WAS 0.3 POUND. CONSTRUCT A 90%
CONFIDENCE INTERVAL FOR THE POPULATION MEAN.
4. A TRAVEL AGENT WISHES TO ESTIMATE WITH A 95% CONFIDENCE INTERVAL THE PROPORTION
OF VACATIONERS WHO TRAVEL OUTSIDE THE US. THE ERROR OF ESTIMATE MUST BE NO MORE
THAN 3%.
(A) IF NO PREVIOUS ESTIMATE IS KNOWN FOR THE SAMPLE PROPORTION, HOW LARGE MUST THE
SAMPLE BE?
(B) IF A PREVIOUS STUDY FOUND A SAMPLE PROPORTION OF 26%, FIND THE SAMPLE SIZE
NEEDED.
5. A STUDY OF 2008 TRAFFIC FATALITIES FOUND THAT 800 WERE ALCOHOL RELATED.
CONSTRUCT A 95% CONFIDENCE INTERVAL FOR THE PROPORTION OF FATALITIES THAT WERE
ALCOHOL RELATED.
6. A CITY PLANNER RANDOMLY SELECTS 110 APARTMENTS IN AN INNER-CITY AREA IN ORDER
TO ESTIMATE THE MEAN LIVING AREA PER APARTMENT. THE SAMPLE YIELDED A MEAN OF 1325
SQ.FT.AND STANDARD DEVIATION OF 42.4. CONSTRUCT A 90% CONFIDENCE INTERVAL FOR THE
MEAN LIVING AREA.
7. IT IS BELIEVED THAT THE AVERAGE LENGTH OF TIME REQUIRED TO COMPLETE A CERTAIN
APTITUDE TEST IS 80 MINUTES. A SAMPLE OF 22 STUDENTS YIELDED AN AVERAGE OF 86.5
MINUTES AND STANDARD DEVIATION OF 15.4 MINUTES. ASSUMING THE PARENT DISTRIBUTION
IS NORMAL, CONSTRUCT A 99% CONFIDENCE INTERVAL FOR THE MEAN LENGTH OF TIME
REQUIRED.
8. APPALACHIAN STATE UNIVERSITY IS LOCATED IN THE TOWN OF BOONE, IN WATAUGA
COUNTY, NORTH CAROLINA. WATAUGA COUNTY IS A DRY COUNTY. :( A RANDOM SAMPLE OF
400 STUDENTS FOUND THAT 230 FAVOR THE SALE OF BEER IN THE COUNTY. CONSTRUCT A 90%
CONFIDENCE INTERVAL FOR THE POPULATION PROPORTION.
9. A PREVIOUS STUDY HAS ESTIMATED THE PROPORTION OF BEAGLES AT A CERTAN KENNEL
WITH A CERTAIN GENETIC TRAIT IS .12. HOW LARGE A SAMPLE OF BEAGLES WOULD BE
REQUIRED TO ESTIMATE THE PROPORTION OF BEAGLES WITH THE TRAIT WITH A 95%
CONFIDENCE INTERVAL ACCURATE TO WITHIN 4%?
5. HOW LARGE A SAMPLE OF BEAGLES WOULD BE REQUIRED TO ESTIMATE THE MEAN LENGTH
OF BEAGLES’ TAILS WITH A 99% CONFIDENCE INTERVAL ACCURATE TO WITHIN 0.5 INCHES?
ASSUME A PREVIOUS SURVEY FOUND A STANDARD DEVIATION OF 1.2 INCHES.