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Finding the Fourth Proportional to 1,390.96, 1,918.68 and 918.86

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Solution

The fourth proportional to 1,390.96, 1,918.68 and 918.86 is: 1,267.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.96 : 1,918.68 = 918.86 : x
  2. Step 2: Convert to fraction form
    1,390.96/1,918.68 = 918.86/x
  3. Step 3: Cross multiply
    1,390.96x = 1,918.68 × 918.86
  4. Step 4: Simplify right side
    1,390.96x = 1,762,998.30
  5. Step 5: Solve for x
    x = 1,762,998.30/1,390.96
  6. Step 6: Final answer
    x = 1,267.47

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1.5x scale

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.