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Finding the Fourth Proportional to 985.74, 1,475.66 and 638.40

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Solution

The fourth proportional to 985.74, 1,475.66 and 638.40 is: 955.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    985.74 : 1,475.66 = 638.40 : x
  2. Step 2: Convert to fraction form
    985.74/1,475.66 = 638.40/x
  3. Step 3: Cross multiply
    985.74x = 1,475.66 × 638.40
  4. Step 4: Simplify right side
    985.74x = 942,061.34
  5. Step 5: Solve for x
    x = 942,061.34/985.74
  6. Step 6: Final answer
    x = 955.69

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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.