[Chocotaco]

A 0.200 M solution of a weak acid has a [H⁺¹] = 1.84 x 10^-3 M. What is Ka of this weak acid?

I'm pretty sure I got this question right but the answer says it's 1.80 x 10^-5, I keep getting around 1.70 x 10^-5. Just want a second opinion if I did something wrong along the way.

HA <--> H⁺¹ + A^-1
Ka = [H+][A-] / [HA]
[H+] = 1.84 x 10^-3
[A-] = [H+]
[HA] = 0.200 - 1.84 x 10^-3 = .19816
Ka = (1.84 x 10^-3)² / .19816 = 1.70 x 10^-5

[rabolisk]

You are correct. It looks like a typo.

[Chocotaco]

Oh ok thanks, that's what I thought.