Question

find the 4th proportion 5, 9, 45.

Answer 1

Answer:

5:9:: 45:x

5×x=9×45

x=9×45÷5

9×9 =81 answer

Answer 2

Answer:

given:

5:9::45:x

Product of extreme= product of means

$5 \times x = 9 \times 45 \\ 5x = 405 \\ x = 405 \div 5 \\ x = 81$

hence, fourth proportion = 81