Set S consists of positive numbers. If -1 is added as an element to set S, which of the following is impossible ?
The mean will decrease but median will not change.
The median will decrease but mean will not change.
The range will increase but median will not change.
The range will increase but mean will decrease.
The standard deviation will increase but mean will decrease.
what is the best way to test this.. Am getting bogged down by picking numbers .. Also on picking numbers am unable to decide between A B and C - all seem impossible. Pl help
The mean of set S is sum/n, where n is # of terms in set S.
Since set S consist of positive numbers, then when we add -1 to the set the sum of the numbers in the new set will decrease. So, the new mean will be (less sum)/(more terms)=(less sum)/(n+1), which will be less than the sum/n. Hence the mean must decrease.
Answer: B.P.S. If it's GMAT Club question please site # of test and # of question.
NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!
PLEASE READ AND FOLLOW: 11 Rules for Posting!!!
RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;
COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat
DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.
What are GMAT Club Tests?
25 extra-hard Quant Tests
Get the best GMAT Prep Resources with GMAT Club Premium Membership