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Finding the Fourth Proportional to 918.20, 1,376.10 and 661.40

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Solution

The fourth proportional to 918.20, 1,376.10 and 661.40 is: 991.24

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.20 : 1,376.10 = 661.40 : x
  2. Step 2: Convert to fraction form
    918.20/1,376.10 = 661.40/x
  3. Step 3: Cross multiply
    918.20x = 1,376.10 × 661.40
  4. Step 4: Simplify right side
    918.20x = 910,152.54
  5. Step 5: Solve for x
    x = 910,152.54/918.20
  6. Step 6: Final answer
    x = 991.24

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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.