Aim High
'On a mercator chart the distance between two meridians 1deg apart is 7.45cm. What is the scale at 48degN?'
The distance between the two meridians is at 48 N is found by departure formula:
Dep (in NM) = dlong in min x cos mlat
Dep (in NM) = (1 x 60 x cos 48)
Dep (in NM) = 40.147836381
1 / d = CL / ED
1 / d = 7.45 cm / 7435379.29785963 cm
d = 991383.9 (approximately 1,000,000)
The scale at the Equator could also be found if requested
Since on a std Mercator scale expands as a function of secant lat
secant lat = 1 / cos lat
New d / Old d = Old secant lat / New secant lat
Must rush dinner on table (lol)