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Finding the Fourth Proportional to 783.12, 1,079.40 and 688.35

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Solution

The fourth proportional to 783.12, 1,079.40 and 688.35 is: 948.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    783.12 : 1,079.40 = 688.35 : x
  2. Step 2: Convert to fraction form
    783.12/1,079.40 = 688.35/x
  3. Step 3: Cross multiply
    783.12x = 1,079.40 × 688.35
  4. Step 4: Simplify right side
    783.12x = 743,004.99
  5. Step 5: Solve for x
    x = 743,004.99/783.12
  6. Step 6: Final answer
    x = 948.78

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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.