If $a:b=2:3$, $b:c=5:6$ and $c:d=8:11$ then find $a:d$.

Given,

$a:b=2:3$

or, $\frac{a}{b}=\frac{2}{3}$......(1).

And

$b:c=5:6$ 

or, $\frac{b}{c}=\frac{5}{6}$.......(2)

And $c:d=8:11$

or, $\frac{c}{d}=\frac{8}{11}$........(3).

Now multiplying (1) and (2) and (3) we get,

$\frac{a}{d}=\frac{40}{99}$

or, $a:d=40:99$.