Question

A submarine begins its descent from the surface of the water. If it dives 5/2 metres each minute for
16 minutes, what is the final position of the submarine? Write your answer as a rational number.​

Answer 1

Answer:

18 mins.

Explanation:

Time taken to travel 20 m = 1 min

Time taken to travel 360m =

x

min

therefore:

1

20=x360

(cross multiply)

20

x

=360

(isolate

x

by dividing both sides by 20)

x

=

360

20

x = 18 mins.

Answer 2

The position of the Submarine is 40 meters depth from the top of the water surface

Given:

A submarine begins its descent from the surface of the water.

If it dives 5/2 metres each minute.

To find:

what is the final position of the submarine

Solution:

A submarine descent from the surface of the water

The submarine dives 5/2 metres each minute

5/2 = 2.5 meters

The submarine dives 2.5 metres for each minute

⇒ For 2 mins the Submarine position = 2 × 2.5 = 5 meters

5 m depth from top of the water surface

⇒ For n mins the Submarine position = n × 2.5 = 2.5n meters

2.5n meters depth from top of the water surface

Just like that after 16 mins the Submarine position = 16 (2.5) = 40 meters  

After 16 meters the Submarine will at 40 meters depth from top of the water surface

The position of the Submarine is 40 meters depth from the top of the water surface

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