यदि `A : B = 3 : 4m B : C = 5 : 7` और `C : D = 8.9` तब A : D किसके बराबर है?

Options

A. `3:7`
B. `7:3`
C. `21: 10`
D. `10 : 21`

Answer

D

Explanation

`{:("A : B","B : C","C : D"),("3 : 4","5 : 7","8 : 9"):}`
`(A)/(B)=(3)/(4),(B)/(C)=(5)/(7)=(C)/(D)=(8)/(9)`
`(A)/(B)xx(B)/(C)xx(C)/(D)rArr(3)/(4)xx(5)/(7)xx(8)/(9)`
`rArr (10)/(21)`
`A : D = 10 :21`