Which azimuth closure formula involves the largest coefficient in front of √N?

• A. 1.7√N
• B. 3.0√N
• C. 10.0√N
• D. 4.5√N

Answer: (C)

In azimuth closure estimates, the size of the closure term scales with a coefficient in front of the square root of N, because errors tend to accumulate like a random walk as you include more measurements. The larger that coefficient, the larger the predicted closure for any given N. Among the options, the coefficients are 1.7, 3.0, 10.0, and 4.5 in front of √N. The largest coefficient is 10.0, so the formula 10.0√N gives the largest azimuth closure term for the same N. The other options have smaller coefficients, producing smaller closures.