Tan Y J's answer to huihuibuhui's Junior College 1 H1 Maths Singapore question.
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For part b
Let x be the number of data Benjamin uses and y be the total cost of plan selected
y=19+5x -(A)
y=39+5(x-2)
=29+5x -(B)
y=79 -(C)
Comparing plans A and C
79<19+5x
60<5x
x>12
Plan A is cheaper than plan B regardless of the amount of GB of data he used. Hence he should select plan A if he uses less than 12 GB of data
However if Benjamin uses more than 12 GB of data, he should select plan C as it is cheaper than plan A
Let x be the number of data Benjamin uses and y be the total cost of plan selected
y=19+5x -(A)
y=39+5(x-2)
=29+5x -(B)
y=79 -(C)
Comparing plans A and C
79<19+5x
60<5x
x>12
Plan A is cheaper than plan B regardless of the amount of GB of data he used. Hence he should select plan A if he uses less than 12 GB of data
However if Benjamin uses more than 12 GB of data, he should select plan C as it is cheaper than plan A
Date Posted:
4 years ago
Alternatively, input the three eqns into Gc and sketch. Then explain accordingly
Thank you so much:)
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