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Finding the Fourth Proportional to 987.08, 1,361.86 and 561.65

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Solution

The fourth proportional to 987.08, 1,361.86 and 561.65 is: 774.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.08 : 1,361.86 = 561.65 : x
  2. Step 2: Convert to fraction form
    987.08/1,361.86 = 561.65/x
  3. Step 3: Cross multiply
    987.08x = 1,361.86 × 561.65
  4. Step 4: Simplify right side
    987.08x = 764,880.46
  5. Step 5: Solve for x
    x = 764,880.46/987.08
  6. Step 6: Final answer
    x = 774.90

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.