The time, T
(seconds), it takes for a pot of water to boil is proportional to the amount,
A
(litres), of water.
It takes 180 seconds to boil 2.8 litres of water.
Work out how long it takes (to the nearest second) to boil 2.2 litres.

The time it takes to boil 2.2 litres of water is approximately 141 seconds

Step-by-step explanation:

The given parameters are;

The relationship of the variables, T and A is a proportional, therefore, we have;

T ∝ A, or T/A = k = Constant of proportionality

The time it takes to boil 2.8 liters of water = 180 seconds

∴ When A = 2.8 litres, T = 180 seconds, from which we have;

k = T/A = 180 s/(2.8 L) = 450/7 s/L

k = 450/7 s/L

When A = 2.2 litres, we have;

T/A = k

∴ T = k × A

Plugging in the value for both 'k', and 'A' when A = 2.2 litres, gives;

T = k × A = 450/7 s/L × 2.2 L = 990/7 s = 141. s

The time it takes to boil 2.2 litres of water, given a direct proportionality relation is, T = 141. seconds ≈ 141 seconds given to the nearest second.

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step-by-step explanation: