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Question

A woman starts shopping with Rs. $X$ and $Y$ paise, spends Rs. 3.50 and is left with Rs. $2Y$ and $2X$ paise. The amount she started with is

The correct answer is
Rs. 32.14

This solution explains how to find the initial amount a woman started shopping with, given the amount spent and the remaining amount in terms of variables.

Algebraic Representation of Amounts

Let the starting amount be Rs. $X$ and $Y$ paise.

  • Total starting amount in paise: $100X + Y$
  • Amount spent: Rs. 3.50 = 350 paise
  • Remaining amount: Rs. $2Y$ and $2X$ paise = $100(2Y) + 2X$ paise

Formulating the Equation

The relationship between these amounts is:

Starting Amount - Amount Spent = Remaining Amount

Substituting the expressions in paise:

$(100X + Y) - 350 = 100(2Y) + 2X$

Simplifying the equation:

$100X + Y - 350 = 200Y + 2X$

$100X - 2X + Y - 200Y = 350$

$98X - 199Y = 350$

Verifying the Correct Option

The correct answer is Rs. 32.14. This implies that for the starting amount, $X = 32$ (Rupees part) and $Y = 14$ (Paise part).

We test these values in the derived equation:

Left Hand Side (LHS): $98X - 199Y = 98(32) - 199(14)$

$LHS = 3136 - 2786 = 350$

Right Hand Side (RHS): $350$

Since $LHS = RHS$, the values $X=32$ and $Y=14$ are correct.

Confirming Spending and Remaining Amount

Let's confirm the transaction details:

  • Starting Amount = Rs. 32.14
  • Amount Spent = Rs. 3.50
  • Calculated Remaining Amount = Rs. 32.14 - Rs. 3.50 = Rs. 28.64

Now, let's check the remaining amount based on the formula Rs. $2Y$ and $2X$ paise, using $Y=14$ and $X=32$:

  • Rs. $2Y$ = Rs. $2 \times 14$ = Rs. 28
  • $2X$ paise = $2 \times 32$ paise = 64 paise
  • Remaining amount as per formula = Rs. 28 and 64 paise = Rs. 28.64

The calculated remaining amount matches the amount derived from the formula, confirming the starting amount.

Conclusion

The starting amount is Rs. 32.14.

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Important Questions from Algebra (Notes)

  1. A square matrix having all the elements above the leading diagonal equal to zero is known as:
  2. If $(\frac{7}{11})^{k-5} = (\frac{11}{7})^{k-9}$, find the value of $2^k$.
  3. The sum of the age of A and 5 times the age of B is 36 years. When 3 times the age of A is added to 7 times the age of B, the result is 62 years. The sum of the ages (in years) of A and B is:
  4. 18 bags and 3 pens together cost ₹1,164, whereas 14 bags and 2 pens together cost ₹922. The cost of 9 bags exceeds the cost of 2 pens by:
  5. The cost of 2 pens and 5 notebooks is ₹187. The cost of 8 notebooks exceeds the cost of 4 pens by 40. What is the cost of 8 pens and 7 notebooks?
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