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Finding the Fourth Proportional to 1,438.75, 1,985.57 and 817.75

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Solution

The fourth proportional to 1,438.75, 1,985.57 and 817.75 is: 1,128.55

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,438.75 : 1,985.57 = 817.75 : x
  2. Step 2: Convert to fraction form
    1,438.75/1,985.57 = 817.75/x
  3. Step 3: Cross multiply
    1,438.75x = 1,985.57 × 817.75
  4. Step 4: Simplify right side
    1,438.75x = 1,623,699.87
  5. Step 5: Solve for x
    x = 1,623,699.87/1,438.75
  6. Step 6: Final answer
    x = 1,128.55

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Half scale
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Double scale
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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.