# Tutor profile: Kevin D.

## Questions

### Subject: SAT

What is the average (arithmetic mean) of all the multiples of ten from 10 to 190 inclusive?

To solve this, we add up all of the terms in between and including 10 and 190 to find the total value of all of the multiples, then we divide this value by 19, or the total number of terms, to find the average.

### Subject: Calculus

What is the point behind u-substitution?

When faced with a difficult integral question that has multiple expressions, one of the most basic ways of solving them is by using u-substitution. By setting 'u' equal to the expression with the higher exponent and differentiating this term, one can solve the integral in terms of 'u; and 'du' in a much simpler question.

### Subject: Electrical Engineering

What is the significance behind a XOR Gate?

A XOR Gate is one of the many digital logic gates that provides a True Input when the number of True inputs is odd. This is mainly implemented when building a binary addition calculator.

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