Question about DOE Core study guide question 1.11-7

[BigHat]

The question in the DOE CORE study guide is as follows:

An individual must enter a mixed gamma/neutron radiation field for emergency
repair work. The radiation field consists of 2,500 mR/hr gamma, and 500 mrad/hr
thermal neutron. Assuming the individual has received 340 mrem of his allowable
600 mrem for the month, what is the maximum stay time allowed?

The answer in the book says 3.9 minutes.

If I don't adjust the thermal neutrons with the radiation weighting factor of 5... I do (600-340)/(2500+500) x 60min/hr... and I get 5.2 minutes

If I correct for the radiation weighting factor of 5 for thermal neutrons... I would get (600-340)/(2500+2500) x 60min/hr... and I get 3.12 minutes

I reread 1.06 to make sure I was right on the weighting factor. So I'm stuck...

Am I missing something, or is the study guide wrong?

[S T I G]

The weighting factor for thermal neutrons used to be 3 and now it has been changed to 5. That is why the answer in the book comes out to be 3.9 rather than the 3.12. Don't worry, you're not going crazy.

[BigHat]

okay, awesome. thank you for that, now i know i didn't miss something in the calculation.