Question

Find third proportional to 1/2and 3/4

Answer 1

Answer:

third proportional = 1.125 OR 9/8

Step-by-step explanation:

“The third proportion to a and b is defined as the number x such that a,b,x are in a geometric progression.”

Now, here a = 1/2 = 0.5

b = 3/4 = 0.75  and ‘c’ is to be found.

⇒ a : b = b : c

⇒ 0.5 / 0.75 = 0.75 / c  

⇒  c=  0.75 × 0.75 / 0.5

⇒ c = 0.5625 / 0.5

⇒ c = 1.125

∴ The third proportional to 1/2 and 3/4 is 1.125

                 ***OR***        ***2nd method***

Now, here a = 1/2

b = 3/4 and ‘c’ is to be found.

⇒ a : b = b : c

⇒ 1/2 ÷ 3/4 = 3/4 ÷ c  

⇒  1/2 × c=  3/4 × 3/4

⇒ 1/2 × c = 9/16

⇒ c = 9/ 16 × 2/1

⇒ c = 9/16 × 2

⇒ c = 9/8

∴ The third proportional to 1/2 and 3/4 is 9/8

Its upto you or I would say ask your teacher which way the answer can be written.