Let \(S\) be the set of real numbers with mean \(M\). If the means of the set \(S \cup \{ 15\}\) and \(S \cup \{ 15, 1\}\) are \(M + 2\) and \(M + 1\) respectively, then how many elements does \(S\) have?

This note is part of the set Pre-RMO 2014

Let \(S\) be the set of real numbers with mean \(M\). If the means of the set \(S \cup \{ 15\}\) and \(S \cup \{ 15, 1\}\) are \(M + 2\) and \(M + 1\) respectively, then how many elements does \(S\) have?

This note is part of the set Pre-RMO 2014

No vote yet

1 vote

×

Problem Loading...

Note Loading...

Set Loading...

## Comments

Sort by:

TopNewestAnswer is 4. – Ar Agarwal · 2 years, 7 months ago

Log in to reply

– Rohit Nair · 2 years, 6 months ago

HOW ????????????????????Log in to reply

ans is 4. – Kishan Chaudhary · 1 year, 7 months ago

Log in to reply

4 – Sahil Nare · 2 years ago

Log in to reply

the answer is 4 . equations are y/x=m y+15/x+1=m+2 y+16/x+2=m+1 where y is the sum of numbers and x is the number of elements. thus solving them , we get x=4 – Ärnäv Mändäl · 2 years, 6 months ago

Log in to reply