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Finding the Fourth Proportional to 917.40, 1,264.80 and 720.12

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Solution

The fourth proportional to 917.40, 1,264.80 and 720.12 is: 992.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    917.40 : 1,264.80 = 720.12 : x
  2. Step 2: Convert to fraction form
    917.40/1,264.80 = 720.12/x
  3. Step 3: Cross multiply
    917.40x = 1,264.80 × 720.12
  4. Step 4: Simplify right side
    917.40x = 910,807.78
  5. Step 5: Solve for x
    x = 910,807.78/917.40
  6. Step 6: Final answer
    x = 992.81

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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.