Question

Difficulty: MediumFractions and Rational Numbers

An investment fund allocates its total portfolio assets among three asset classes: stocks, bonds, and real estate. Initially, 512\frac{5}{12} of the total portfolio is invested in stocks and 13\frac{1}{3} of the total portfolio is invested in bonds, with the remaining fraction invested in real estate. If 25\frac{2}{5} of the stock portfolio and 14\frac{1}{4} of the bond portfolio are subsequently liquidated, what fraction of the fund's remaining total portfolio is invested in real estate?

  1. A
    14\frac{1}{4}
  2. B
    310\frac{3}{10}
  3. 13\frac{1}{3}Answer
  4. D
    49\frac{4}{9}
  5. E
    512\frac{5}{12}

Answer

The fraction of the fund's remaining total portfolio invested in real estate is 13\frac{1}{3}.
Let the original total portfolio be TT. Initially, stocks are 512T\frac{5}{12}T, bonds are 412T\frac{4}{12}T, and real estate is 1912T=312T1 - \frac{9}{12}T = \frac{3}{12}T. After liquidating 25\frac{2}{5} of stocks and 14\frac{1}{4} of bonds, the remaining stock value is 35×512T=312T\frac{3}{5} \times \frac{5}{12}T = \frac{3}{12}T and the remaining bond value is 34×412T=312T\frac{3}{4} \times \frac{4}{12}T = \frac{3}{12}T. Real estate remains 312T\frac{3}{12}T. The new total portfolio is 312T+312T+312T=912T=34T\frac{3}{12}T + \frac{3}{12}T + \frac{3}{12}T = \frac{9}{12}T = \frac{3}{4}T. Therefore, real estate represents 3/12T9/12T=39=13\frac{3/12 T}{9/12 T} = \frac{3}{9} = \frac{1}{3} of the remaining total portfolio.

Step-by-Step Solution

1
Determine the initial fraction invested in real estate.
Real estate accounts for 1(512+13)=1912=312=141 - \left(\frac{5}{12} + \frac{1}{3}\right) = 1 - \frac{9}{12} = \frac{3}{12} = \frac{1}{4} of the original total portfolio.
The sum of all three asset fractions must equal 1.
2
Calculate the remaining fractions for stocks and bonds after liquidation.
Remaining stocks = (125)×512=35×512=312\left(1 - \frac{2}{5}\right) \times \frac{5}{12} = \frac{3}{5} \times \frac{5}{12} = \frac{3}{12}. Remaining bonds = (114)×13=34×412=312\left(1 - \frac{1}{4}\right) \times \frac{1}{3} = \frac{3}{4} \times \frac{4}{12} = \frac{3}{12}.
Multiplying the unliquidated fraction by each asset's initial fraction gives its remaining fraction relative to the original total.
3
Calculate the total remaining portfolio fraction.
Total remaining portfolio = 312 (stocks)+312 (bonds)+312 (real estate)=912=34\frac{3}{12} \text{ (stocks)} + \frac{3}{12} \text{ (bonds)} + \frac{3}{12} \text{ (real estate)} = \frac{9}{12} = \frac{3}{4} of the original total portfolio.
Sum the remaining portions of all three asset categories.
4
Compute the ratio of real estate to the remaining total portfolio.
\frac{\text{Real Estate}}{\text{Remaining Total}} = \frac{\frac{1}{4}}{\frac{3}{4}} = \frac{1}{3}.
The question asks for the fraction relative to the new reduced total portfolio.

Key Concept

Sequential Fraction Allocation and Reduced Base Ratios
Estimated Time:1m 30s
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