In the question "waited for Takeshi/1 hour", the answer is "メアリーさんは一時間たけしさんを待ちました。"
Another option, "メアリーさんはたけしさんを一時間待ちました。", is marked wrong.
I think both of these options are correct since the book uses the following as an example in 4.6:
"メアリーさんはそこでたけしさんを一時間待ちました。"
So, the position of "一時間" is flexible.
In the question "waited for Takeshi/1 hour", the answer is "メアリーさんは一時間たけしさんを待ちました。" Another option, "メアリーさんはたけしさんを一時間待ちました。", is marked wrong. I think both of these options are correct since the book uses the following as an example in 4.6: "メアリーさんはそこでたけしさんを一時間待ちました。" So, the position of "一時間" is flexible.