problem 270 and 267 mathcounts

Mathematics
Tutor: None Selected Time limit: 1 Day

1.The digits 2,0,1 and 4 are used to create every possible positive 4 digit integer, with each digit used exactly once in each integer. What is the arithmetic mean of all these integers?

2.How many elements are in the set {x^2-2x+1|x=-5,-4,...,4,5}?

Nov 1st, 2014

The numbers are 

1024, 1042, 1204, 1240, 1402,1420

2012, 2021, 2102, 2120, 2201, 2210

4012, 4021, 4102, 4120, 4201, 4210

Arithmetic mean =2481.333 =2481.3

2. (x-1)^2 

x = -5,-4,-3,-2,-1,0,1,2,3,4,5

There are 11 first coordinates and 11 second coordinates (some of the second coordinates may be equal>

(-5,36), (-4,25),(-3,16),(-2,9),(-1,4),(0,1) ,(1,0),(2,1),(3,4),(4,9), (5,16)

Nov 1st, 2014

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