'An average joe' vs 'An average machine'

[Nigmatullinas]

English Language Tests, Intermediate level

ESL/EFL Test #307 "English Slang Idioms (29)", question 6

He knew he would be able to excel in his job. An average ......... could do any of the required duties.

(a) cat
(b) joe
(c) tool
(d) machine

English Language Tests, Intermediate level

ESL/EFL Test #307 "English Slang Idioms (29)", answer 6

He knew he would be able to excel in his job. An average joe could do any of the required duties.

Correct answer: (b) joe
_________________________

is an average machine correct here?

Nigmatullina

[Mister Micawber]

No. The correct answer is indicated above your question.
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Native English teacher at Mister Micawber's

[Ctnsite]

An average joe means an average person. I think machine totally makes no sense here.