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Finding the Fourth Proportional to 986.61, 1,477.21 and 639.08

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Solution

The fourth proportional to 986.61, 1,477.21 and 639.08 is: 956.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    986.61 : 1,477.21 = 639.08 : x
  2. Step 2: Convert to fraction form
    986.61/1,477.21 = 639.08/x
  3. Step 3: Cross multiply
    986.61x = 1,477.21 × 639.08
  4. Step 4: Simplify right side
    986.61x = 944,059.07
  5. Step 5: Solve for x
    x = 944,059.07/986.61
  6. Step 6: Final answer
    x = 956.88

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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.