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Finding the Fourth Proportional to 991.87, 1,488.55 and 678.77

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Solution

The fourth proportional to 991.87, 1,488.55 and 678.77 is: 1,018.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.87 : 1,488.55 = 678.77 : x
  2. Step 2: Convert to fraction form
    991.87/1,488.55 = 678.77/x
  3. Step 3: Cross multiply
    991.87x = 1,488.55 × 678.77
  4. Step 4: Simplify right side
    991.87x = 1,010,373.10
  5. Step 5: Solve for x
    x = 1,010,373.10/991.87
  6. Step 6: Final answer
    x = 1,018.66

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.