Refer to figure.
Field Length Requirements

a) When no stopway or clearway is available the take-off distance when multiplied by 1.25 must not exceed TORA.
c) If the runway surface is other than dry and paved the following factors must be used when determining the take-off distance in a) or b) above:
Grass (on firm soil) up to 20 cm. Long and dry = x 1.2

• 2250 ft / 1.25 / 1.2 = 1500 ft

To solve this exercise, we must draw 2 lines. The mass will be the value corresponding to the intersection of these 2 lines:
(1) First, enter the graph on the left-hand side, at a temperature of +11ºC. Draw a vertical line up until the 2000 ft pressure altitude reference line. From this intersection, continue horizontally to the right until the mass "REF LINE". Draw a line diagonally down and to the right following the reference lines (all the way to a mass of 3000 lb).
(2) Now, starting at the right-hand side of the graph, from 1500 ft, draw a diagonal line down and to the left, following the obstacle height reference lines until the next "REFERENCE LINE". From this point, continue horizontally and to the left and correct for 5 kt headwind. From the wind Reference Line, continue horizontally and to the left until you intersect the first line.

• Find the value corresponding to approx. 3500 lbs at the intersection of these 2 lines.