# Phy 120 Prelab 2

**Combining Errors**

Before you come to the laboratory, test yourself on your understanding
of combining experimental errors by imagining that a quantity Q is computed from measured
values of x and y according to

#### Q = 10 x/y^{2}.

The values obtained experimentally are (to 90% confidence)

#### x = 5.00 +/- 0.01

#### y = 15.00 +/- 0.03.

**Questions:**

How much is Q uncertain due to the uncertainty of x?

How much is Q uncertain due to the uncertainty of y?

What is the value of Q, to 90% confidence? Be sure to show the
uncertainties combine to obtain the net uncertainty in Q?