Five minutes at the least and one hour at the most.
The minimum is five minutes and the maximum is one hour.
The shortest amount of time I spend on the computer is five minutes and the longest is one hour.
英訳1：at (the) least で「少なくても」、at (the) most で「多くても」という意味です。
英訳2：minimum は「最小限」、maximum は「最大限」なので、長さを表す場合にも使えます。
英訳3：「私がパソコンにかける時間は、(一番) 短くて5分、(一番) 長くて1時間です」という意味になります。
時間の長さについて言う場合、amount of time と言う必要があります。the shortest amount of time ~ is ~ and the longest is ~ となるように、ふたつ目の amount of time は省略されます。
It would take at least five minutes and no more than one hour.
Probably at least five minutes and one hour at the most.
It would take at least five minutes and no more than one hour.
たぶん最低短くても５分、１時間以上はかからないよ。
Probably at least five minutes and one hour at the most.
おそらく最低５分、最長１時間！
I may finish very soon or it could take up to an hour
I'll say an hour, but it could be earlier
To explain this exactly, you could say something like:
"I may finish very soon or it could take up to an hour."
However, that could lead to problems. The person waiting may be pacing up and down beside you like a wolf, peering over your shoulder and waiting for you to finish! This could be quite disturbing for you. Better to say:
"I'll say an hour, but it could be earlier."
これを正確に説明するなら、次のように言うことができます：
"I may finish very soon or it could take up to an hour."
しかし、それが問題になる可能性があります。待っている人は、オオカミのようにあなたの横付して、あなたを肩から覗いて終わるのを待っているかもしれません！あなたにとって非常に邪魔になるかもしれません。い言い方としては：
"I'll say an hour, but it could be earlier."「1時間と言っておくよ、早くなるかもしれないけど」
I'll be on the computer between 5 minutes to an hour.
The two sentences you see above are great ways to express the amount of time you will be on the computer. In the first sentence you will notice that we only mention how long we are going to be. This may give you the amount of time you need instead of the person waiting for you to finish after 5 minutes. I hope this explanation and these two sentences help.
I'm going to use the computer anywhere from 5 minutes to one hour.
It might be five minutes or an hour.
I'll be on the computer between five minutes to a hour
"I'm going to use the computer anywhere from 5 minutes to one hour." states clearly that the time you spend on the computer could be five to sixty minutes.
【例】
"I'm going to use the computer anywhere from 5 minutes to one hour."
（5分から1時間くらいパソコンを使います）
これは、あなたがパソコンを5分から1時間くらい使用することを明確に述べています。
I will be on the computer for about an hour at the longest.
It will be 5 minutes at the least and 1 hour the most.
"I will be on the computer for about an hour at the longest."
"It will be 5 minutes at the least and 1 hour the most"
Both sentences express what you want to convey to the person you are speaking to. In the first sentence you are generalizing not being so specific. On other hand on the second sentence you are being specific on how much time you will be on the computer.
"I will be on the computer for about an hour at the longest."
長くて一時間くらいパソコンを使う。
"It will be 5 minutes at the least and 1 hour the most"
短くて5分、長くて1時間です。
どちらの例でも、伝えたいことを表せます。
一つ目の文ではそこまで詳しく言っていませんね。
二つ目の文ではどのくらいの時間パソコンを使うかについて細かく伝えています。
アメリカ合衆国 
日本 
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