National Instruments Hardware Engineer interview questions

RC circuits and signal conditioning using Opamps

They worked with me through the process of how to implement a system to record a person voice in a computer. They asked the question as stages like, "What would you use?" very general then they asked "But the computer would be able to read the microphone directly?" which was even a tip to know that should put a converter since the microphone output is analog and the computer is only able to read digital signals. It was also asked a pretty basic question about software that was "given an array not ordered which numbers in the range 1-100, suppose it is missing a number how would you proceed to know which number is missing?"