what is wrong with this sentence? (Statistics indicate that approximate every...)

[Chiaki]

Here is the sentence: Statistics indicate that approximate every 22 years - within a range of 3-4 years - a mjor drought occurs in the United Sates

There is only one mistake in it. I thought it was "approximate", which should be approximately instead, but I was wrong. So what is the mistake?

[Mister Micawber]

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'Approximate' is indeed wrong-- it should be 'approximately'.

'Major' and 'States' are misspelt, also.
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Native English teacher at Mister Micawber's

[Chiaki]

[Lost_Soul]

Hi, Chiaki

So, what word does the key offer instead of "indicate" ?

[Chiaki]

[Mister Micawber]

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The key is wrong. 'Approximate' is egregiously incorrect.

Presumably the question writer or transcriber was confused by the fact that 'Statistics', as the name of a discipline, is singular-- forgetting that when meaning the numbers themselves, 'statistics' is very plural.
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Native English teacher at Mister Micawber's