Question 711587
You have a formula to calculate {{{H}}}.
All you have to do is plug into that formula the values given for {{{d}}} and {{{E}}}.
 
As I read it, the formula is
{{{H=0.00252d^2.27/E}}}, with just {{{2.27}}} as the exponent
Substituting {{{d=50}}} and {{{E=1.2}}} we get
{{{H=0.00252*50^2.27/1.2=15}}} (rounded)
so the letters would have to be 15 meters tall.
That is very tall, but very tall letters may be needed for such a long distance.
 
If the formula was really
{{{H=0.00252d^((2.27/E))^instead}}}, with {{{2.27/E}}} as the exponent,
then the calculated distance is shorter
{{{H=0.00252*50^((2.27/1.2))^instead}}} and that is
{{{H=0.00252*50^1.89=4.1}}}
and the calculated letter height is 4.1 meters.