F.2 Mathz

1)Speed = Distance travelled / Time

Speed of yacht = 240 / 4 = 60 km/h
Speed of speedboat = 225 / 3 =75 km/h

The ratio of the speed of the yacht to that of the speedboat = 60 / 75 =4 : 5 (no unit is required)

2) Let x be the no. of boy scouts
y be the no. of girl guides

Since the number of boy scouts and that of girl guides are in the ratio 3:5,
x/y = 3/5 => 5x = 3y ... (1)

Also y = x + 8 ...(2)

Putting (2) into (1),
5x = 3(x + 8)
5x = 3x + 24
2x = 24
x = 12

From (2), y = 12 + 8 =20

Therefore, the total number of boy scouts and girl guides in the school are 12 and 20 respectively.