Math Is Fun Forum

netddos

Member

Registered: 2006-10-11

Posts: 2

SAT Math question #20

The least integer in a set of consecutive integers is x. The greatest integer in the set is z. If the sum of these integers is y, which of the following represents thenumber of integers in this set?

a) z-x

b) x-z+1

c) (x+y) / z

d) y-x+z

e) 2y/ (x+z)

I don't get this at all..

Let say.. set A is defined as this { 2,3,4,5,6 }

so

x= 2
z= 6
y= 8

by inputting those values according to those options above, i should get 5...

but i don't...what the heck am i doing wrong?

pi man

Member

Registered: 2006-07-06

Posts: 251

Re: SAT Math question #20

You're not doing any thing wrong.   The correct solution isn't listed.   It should be z-x+1.

polylog

Member

Registered: 2006-09-28

Posts: 162

Re: SAT Math question #20

Indeed, for any closed interval of integers [a, b], the the number of integers in it is (b - a + 1). The question doesn't have the right answer listed.

Last edited by polylog (2006-10-11 03:25:53)

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: SAT Math question #20

y is the sum of all the integers, not just x and z.

So in your example, y = 2+3+4+5+6 = 20.

e) is the correct answer, because it is the same as z-x+1, just written in a different form.

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Why did the vector cross the road?
It wanted to be normal.

netddos

Member

Registered: 2006-10-11

Posts: 2

Re: SAT Math question #20

wow...so subtle..

sneeky sat makers..i hate them..

thank you for catching that for me..

MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,711

Re: SAT Math question #20

Well done, mathsy!

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"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman