"at least 150" or "(much) more than 150"?

[Yuji]

English Language Tests, Intermediate level

ESL/EFL Test #146 "Conversations and Comprehension Test", question 10

Jane: How many people were at Brad's wedding?
Bruce: Oh, there must have been at least 150 people there. The reception hall was really big, and it was nearly full of guests. We had a great time.
Jane: That's great.
Question: How many people were at Brad's wedding? ..........

(a) Much more than 150 people
(b) About 150 people
(c) Fewer than 150 people

English Language Tests, Intermediate level

ESL/EFL Test #146 "Conversations and Comprehension Test", answer 10

Jane: How many people were at Brad's wedding?
Bruce: Oh, there must have been at least 150 people there. The reception hall was really big, and it was nearly full of guests. We had a great time.
Jane: That's great.
Question: How many people were at Brad's wedding? About 150 people.

Correct answer: (b) About 150 people

Your answer was: incorrect
Jane: How many people were at Brad's wedding?
Bruce: Oh, there must have been at least 150 people there. The reception hall was really big, and it was nearly full of guests. We had a great time.
Jane: That's great.
Question: How many people were at Brad's wedding? Much more than 150 people.
_________________________

Hi, I just want to ask a question.
If you say "at least 150" so doesn't it mean "(much) more than 150" ?

[Mister Micawber]

.
It means a minimum of 150. It could be 151 or 200.
.
_________________
Native English teacher at Mister Micawber's

[Yuji]

Thank you for your answer.
However, if you say "about 150", from what I think, it is around 150, say, 140 to 160. So the answer is not (entirely) correct?
Correct me, please, if I'm mistaken.

[Mister Micawber]

.
I agree that the question needs reworking. Thanks for bringing it to our attention, Yuji-san.
.
_________________
Native English teacher at Mister Micawber's

[Yuji]

oh, arigato gozaimasu. Thank you for quick answer. I really appreciate it.
I've just noticed , by the way,that you're from Yokohama.
Yuji

[Mister Micawber]

.
Yes, I've been teaching English here for almost 20 years now. Where do you live, Yuji?
.
_________________
Native English teacher at Mister Micawber's

[Yuji]

I live in Tokyo, very near Yokohama
Yuji