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Finding the Fourth Proportional to 916.40, 1,263.92 and 621.15

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Solution

The fourth proportional to 916.40, 1,263.92 and 621.15 is: 856.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    916.40 : 1,263.92 = 621.15 : x
  2. Step 2: Convert to fraction form
    916.40/1,263.92 = 621.15/x
  3. Step 3: Cross multiply
    916.40x = 1,263.92 × 621.15
  4. Step 4: Simplify right side
    916.40x = 785,080.80
  5. Step 5: Solve for x
    x = 785,080.80/916.40
  6. Step 6: Final answer
    x = 856.71

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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.