Question

Latitude and longitude describe locations on the Earth with respect to the equator and prime meridian. The table shows the latitude and daily high temperatures on the first day of spring for different locations with the same longitude.

A 2-row table with 9 columns. The first row is labeled latitude (degrees North) with entries 42, 45, 39, 35, 32, 41, 40, 33, 30. The second row is labeled high temperature (degrees Fahrenheit) with entries 53, 51, 67, 63, 70, 58, 61, 67, 72.

Which statement describes the slope of the line of best fit for the data?

The temperature decreases by about 0.9° for each 1 degree increase north in latitude.
The temperature decreases by about 1.7° for each 1 degree increase north in latitude.
The temperature increases by about 0.8° for each 1 degree increase north in latitude.
The temperature increases by about 1.3° for each 1 degree increase north in latitude.

Answer 1

Compute the least-squares slope: m = [nΣ(xy) − ΣxΣy] / [nΣ(x^2) − (Σx)^2] = −2482/1892 ≈ −1.31.

So temperature decreases by about 1.3°F for each 1° increase north in latitude. (None of the four choices exactly match this wording; the closest supplied numeric value is 1.3°F, but the correct sign is "decreases".)