It would take 150 minutes to fill a swimming pool using 5 taps.
a) How many minutes will it take to fill the pool if only 3 of the taps are used?

Complete the following.
b) An assumption being made in my working is that all the taps are flowing at the same time.

  250 minutes

Step-by-step explanation:

a) Assuming all taps flow at the same rate, the time is inversely proportional to the number of taps. Using 3/5 of the total taps will take 5/3 of the time required when all taps are used.

For 3 taps, the time is ...

  (5/3)(150 minutes) = 250 minutes

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b) An assumption being made in my working is that all the taps are flowing at the same rate.

x = ±sqrt(10)

step-by-step explanation:

5 - 2x² = -15

subtract 5 from each side

5-5 - 2x² = -15-5

-2x^2   = -20

divide by -2 on each side

-2x^2   /-2= -20/-2

x^2 =10

take the square root on each side

sqrt(x^2 )=±sqrt(10)

x = ±sqrt(10)

check:

5 - 2x² = -15

+sqrt(10)

5 - 2(sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15

-sqrt(10)

5 - 2(-sqrt(10))² = -15

5 -2(10) = -15

5 -20 = -15

-15 = -15