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Mathematics

An employer finds that if he increases the weekly wages of each worker by ₹ 5 and employs five workers less, he increases his weekly wage bill from ₹ 3150 to ₹ 3250. Taking the original weekly wage of each worker as ₹ x; obtain an equation in x and then solve it to find the weekly wages of each worker.

Quadratic Equations

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Answer

Initial weekly wage = ₹ 3150,

Let weekly wage of each worker be ₹ x,

No. of employees = 3150x\dfrac{3150}{x}

New wage = ₹ (x + 5)

No. of employees after reducing 5 employees = 3150x\dfrac{3150}{x} - 5

Given, new total wage = ₹ 3250

(x+5)(3150x5)=3250(x+5)(31505xx)=3250(x+5)(31505x)x=32503150x5x2+1575025x=3250x5x2+3250x3150x+25x15750=05x2+125x15750=05(x2+25x3150)=0x2+25x3150=0x2+70x45x3150=0x(x+70)45(x+70)=0(x45)(x+70)=0x45=0 or x+70=0x=45 or x=70.\Rightarrow (x + 5)\Big(\dfrac{3150}{x} - 5\Big) = 3250 \\[1em] \Rightarrow (x + 5)\Big(\dfrac{3150 - 5x}{x}\Big) = 3250 \\[1em] \Rightarrow \dfrac{(x + 5)(3150 - 5x)}{x} = 3250 \\[1em] \Rightarrow 3150x - 5x^2 + 15750 - 25x = 3250x \\[1em] \Rightarrow 5x^2 + 3250x - 3150x + 25x - 15750 = 0 \\[1em] \Rightarrow 5x^2 + 125x - 15750 = 0 \\[1em] \Rightarrow 5(x^2 + 25x - 3150) = 0 \\[1em] \Rightarrow x^2 + 25x - 3150 = 0 \\[1em] \Rightarrow x^2 + 70x - 45x - 3150 = 0 \\[1em] \Rightarrow x(x + 70) - 45(x + 70) = 0 \\[1em] \Rightarrow (x - 45)(x + 70) = 0 \\[1em] \Rightarrow x - 45 = 0 \text{ or } x + 70 = 0 \\[1em] \Rightarrow x = 45 \text{ or } x = -70.

Since wage cannot be negative,

∴ x ≠ -70.

Hence, weekly wage of worker = ₹ 45 and quadratic equation = x2 + 25x - 3150 = 0.

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