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Finding the Fourth Proportional to 980.78, 1,351.65 and 666.06

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Solution

The fourth proportional to 980.78, 1,351.65 and 666.06 is: 917.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    980.78 : 1,351.65 = 666.06 : x
  2. Step 2: Convert to fraction form
    980.78/1,351.65 = 666.06/x
  3. Step 3: Cross multiply
    980.78x = 1,351.65 × 666.06
  4. Step 4: Simplify right side
    980.78x = 900,271.58
  5. Step 5: Solve for x
    x = 900,271.58/980.78
  6. Step 6: Final answer
    x = 917.92

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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.