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Finding the Fourth Proportional to 913.80, 1,261 and 515.40

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Solution

The fourth proportional to 913.80, 1,261 and 515.40 is: 711.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    913.80 : 1,261 = 515.40 : x
  2. Step 2: Convert to fraction form
    913.80/1,261 = 515.40/x
  3. Step 3: Cross multiply
    913.80x = 1,261 × 515.40
  4. Step 4: Simplify right side
    913.80x = 649,919.40
  5. Step 5: Solve for x
    x = 649,919.40/913.80
  6. Step 6: Final answer
    x = 711.23

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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.