presumptuous

She was presumptuous to think she could lead the project without any experience.

彼女が経験なしにプロジェクトを指導できると思うのは思い上がりだった。

It was presumptuous of him to assume he would get the job without an interview.

面接なしで仕事を得られると考えるとは、彼は僭越だった。