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Finding the Fourth Proportional to 987.56, 1,479.60 and 621.50

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Solution

The fourth proportional to 987.56, 1,479.60 and 621.50 is: 931.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.56 : 1,479.60 = 621.50 : x
  2. Step 2: Convert to fraction form
    987.56/1,479.60 = 621.50/x
  3. Step 3: Cross multiply
    987.56x = 1,479.60 × 621.50
  4. Step 4: Simplify right side
    987.56x = 919,571.40
  5. Step 5: Solve for x
    x = 919,571.40/987.56
  6. Step 6: Final answer
    x = 931.15

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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.