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Oksana_A [137]
2 years ago
13

6 water pumps fill a water tank in 15 hours if they work together. a) If one of these pumps is not working, how long will the 5

water pumps take to fill the tank? b) If we want the tank filled in 9 hours, how many water pumps do we need?​
Mathematics
1 answer:
Elodia [21]2 years ago
3 0

Answer:

a) 18 hours

b) 10 water pumps

Step-by-step explanation:

<em>• We notice that we are in an inverse proportion situation </em>

<em>because</em><em> </em><em>when the number of pumps increase the number </em>

<em>of hours taken to fill the tank decrease  and vice versa</em>.

<em>Formula</em> :

<u>in an inverse proportional relation :</u>

<u>the product of the two variables = a constant (k)</u>

……………………………………………………………………………

let p be the number of pumps

and h be the number of hours

By applying the formula we get :

p × h = k

Then the constant of proportionality :

k = 6 × 15 = 90

a)

5 × h = 90

Then

h = 90/5

  = 18

b)

p × 9 = 90

Then

p = 90/9

  = 10

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