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Finding the Fourth Proportional to 1,290, 1,780.74 and 917.04

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Solution

The fourth proportional to 1,290, 1,780.74 and 917.04 is: 1,265.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290 : 1,780.74 = 917.04 : x
  2. Step 2: Convert to fraction form
    1,290/1,780.74 = 917.04/x
  3. Step 3: Cross multiply
    1,290x = 1,780.74 × 917.04
  4. Step 4: Simplify right side
    1,290x = 1,633,009.81
  5. Step 5: Solve for x
    x = 1,633,009.81/1,290
  6. Step 6: Final answer
    x = 1,265.90

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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.