Question

7. The third proportional of 1 hr 20 minutes, 1 hr 40 minutes is 2 hrs. ​

Answer 1

Answer:

Let the third proportional to 12 and 30 be x.

Then, 12 : 30 :: 30 : x

⇔ 12x = 30 × 30

⇔x=

12

(30×30)

=75

∴ Third proportional to 12 and 30 = 75.

Mean proportional between 9 and 25=

9×25

=15

∴ Required ratio = 75 : 15 = 5 : 1.

Answer 2

Answer:

1 hour 20 minutes = 80 minutes

1 hour 40 minutes = 100 minutes

Let 3rd proportion be x

then,

80/100=100/x

= 125 minutes

= 2 hour 5 minutes (c)

Ans-(c)

Sol.

let x min be the third proportion.

therefore,

80min/100min=100min/x,

x=10000min/80min=125 min

i.e; x=2 hrs 5 minutes....Ans

x min be the third proportion.

80min/100min=100min/x,

x=10000min/80min=125 min

i.e; x=2 hrs 5 minutes