How to find this boiling point

What is the expected boiling-point elevation of water for a solution that contains 150g of sodium chloride dissolved in 1.0 kg of water?

The text book gives me an answer but I don't know how to solve it.
The answer given was: 2.7 degrees C

use molar mass, to find moles
(150g of sodium chloride) (1 mole NaCl / 58.45 grams) = 2.566 moles of NaCl

2.566 moles of NaCl releases twice that in total moles of Na+1 & Cl-1 ions = 5.133 moles

find molality
( 5.133 moles of ions) / 1.0 kg water = 5.133 molal solution

by the boiling point elevation constant
http://en.wikipedia.org/wiki/Boiling-poi…
dT = Kb (molality)

dT = (0.521 C/molal) ( 5.133 molal solution)

dT = 2.674 Celsius rise in boiling point
your answer, rounded to the nearest 1/10 degree Celsius is
+ 2.7 C elevation in B.P.