Induction Motor Speed Regulation NCEES Question with Typo in Solution?

[wfg42438]

In the question below we are asked to determine the speed regulation of the induction motor.

From what i recall and see in the NCEES handbook confirms that this is done using the following formula:

slip=(Ns-N / NS )*100

For some reason the solution uses N instead of Ns as the term in the denominator
Isnt this a typo?

Shouldn't the denominator be Ns leading to a final answer of 2.2% not 2.3% using the equation given by NCEES?

 

[Ekmast]

I am wondering the same. The published Errata doesn’t list it as an error though