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]

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

'Major' and 'States' are misspelt, also.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mister Micawber

[chiaki]

[lost_soul]

Hi, Chiaki

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

Sweet home Alabama
Where the skies are so blue
Sweet home Alabama
I'm comin' home to you

[chiaki]

[Mister Micawber]

.
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.
.
_________________
Canadian-American native speaker
who teaches English for a living at Mister Micawber's
ESL cafe: Interview with Mister Micawber