Typo in introductory statistics book Mistake in book. This is an example from an indtroduction to the central limit theorem written by a professor at my university. Is this a typo?

 A: You hit the jackpot on this one: Three errors
instead of one.
(a) As @Gae.S. says, and you have suggested in
your handwritten note, there needs to be mention of the exponential distribution with parameter $\lambda=1.$
(b) As you have commented, the z score should be $(150-144)/12,$ not $(144-140)/12$ so the normal approximation is $0.6915 \approx 0.69.$
pnorm(.5)
[1] 0.6914625

(c) In addition, $n = 144$ is not quite large
enough for a good normal approximation. The
correct value is $P(T_{144} < 150) = 0.6988 \approx 0.70,$
as computed in R because $T_{144}\sim
\mathsf{Gamma}(\mathrm{shape}=144,\mathrm{rate}=1),$
as can be shown by moment generating functions.
pgamma(150, 144, 1)
[1] 0.6987842

If the purpose is to show how fast or slowly
the CLT converges, there may be some point to using
a normal approximation. But if one wants the
correct answer to even two places it is
necessary to use the exact distribution theory for $n = 144.$ Because of its marked skewness the exponential distribution "converges slowly to normal'.
A better exercise might be to look at $P(T_{625}< 630) = 0.58,$ to two place
accuracy by either method.
pgamma(630, 625, 1)
[1] 0.5842562
pnorm((630-625)/25)
[1] 0.5792597

Note: Any textbook author has to face the fact that
his or her book will contain errors. I am always appreciative when errors are brought to my attention, hoping in vain
for an error-free second (or $n+1$st) edition. I hope you will send the professor a brief 'possible erratum' email about (a) and (b), and perhaps noting the numerical discrepancy in (c).
