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Finding the Fourth Proportional to 1,389.70, 1,918.11 and 917.68

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Solution

The fourth proportional to 1,389.70, 1,918.11 and 917.68 is: 1,266.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.70 : 1,918.11 = 917.68 : x
  2. Step 2: Convert to fraction form
    1,389.70/1,918.11 = 917.68/x
  3. Step 3: Cross multiply
    1,389.70x = 1,918.11 × 917.68
  4. Step 4: Simplify right side
    1,389.70x = 1,760,211.18
  5. Step 5: Solve for x
    x = 1,760,211.18/1,389.70
  6. Step 6: Final answer
    x = 1,266.61

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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.