Question

3. Find the ratio of the third proportional to
12 and 30 to the mean proportional
between 9 and 25.
(1) 5:1
(2) 13:5 (3) 12:5
(4) 1:5
(5) None of these
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Answer 1

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Answer:

1 ) 5:1

Answer 2

Answer:

option 1

Step-by-step explanation:

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.