In what ratio must the grocer mix two types of pulses costing ₹ 15/kg and ₹ 20/kg respectively so as to get una a mixture of pulses costing ₹ 16.50/kg ? 

Given:

Cost of pulse 1 = ₹15/kg

Cost of pulse 2 = ₹20/kg

Cost of mixture = ₹16.50/kg

Formula used:

Using the rule of alligation:

Let the ratio be x : y

\(( \dfrac{\text{Higher Price} - \text{Mean Price}}{\text{Mean Price} - \text{Lower Price}} )\)

Calculation:

\(( \dfrac{20 - 16.50}{16.50 - 15} )\)

⇒ \(( \dfrac{3.50}{1.50} )\)

⇒ \(( \dfrac{7}{3} )\)

∴ The correct answer is (7 : 3).