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Finding the Fourth Proportional to 975.20, 1,345.86 and 643.70

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Solution

The fourth proportional to 975.20, 1,345.86 and 643.70 is: 888.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    975.20 : 1,345.86 = 643.70 : x
  2. Step 2: Convert to fraction form
    975.20/1,345.86 = 643.70/x
  3. Step 3: Cross multiply
    975.20x = 1,345.86 × 643.70
  4. Step 4: Simplify right side
    975.20x = 866,323.35
  5. Step 5: Solve for x
    x = 866,323.35/975.20
  6. Step 6: Final answer
    x = 888.36

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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.