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Finding the Fourth Proportional to 820.80, 1,130.40 and 710.40

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Solution

The fourth proportional to 820.80, 1,130.40 and 710.40 is: 978.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    820.80 : 1,130.40 = 710.40 : x
  2. Step 2: Convert to fraction form
    820.80/1,130.40 = 710.40/x
  3. Step 3: Cross multiply
    820.80x = 1,130.40 × 710.40
  4. Step 4: Simplify right side
    820.80x = 803,036.16
  5. Step 5: Solve for x
    x = 803,036.16/820.80
  6. Step 6: Final answer
    x = 978.36

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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.