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Finding the Fourth Proportional to 646.85, 970.40 and 256.78

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Solution

The fourth proportional to 646.85, 970.40 and 256.78 is: 385.21

Step by Step Solution

  1. Step 1: Write the proportion equation
    646.85 : 970.40 = 256.78 : x
  2. Step 2: Convert to fraction form
    646.85/970.40 = 256.78/x
  3. Step 3: Cross multiply
    646.85x = 970.40 × 256.78
  4. Step 4: Simplify right side
    646.85x = 249,174.46
  5. Step 5: Solve for x
    x = 249,174.46/646.85
  6. Step 6: Final answer
    x = 385.21

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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.