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Finding the Fourth Proportional to 1,385.78, 2,078.69 and 345.78

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Solution

The fourth proportional to 1,385.78, 2,078.69 and 345.78 is: 518.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,385.78 : 2,078.69 = 345.78 : x
  2. Step 2: Convert to fraction form
    1,385.78/2,078.69 = 345.78/x
  3. Step 3: Cross multiply
    1,385.78x = 2,078.69 × 345.78
  4. Step 4: Simplify right side
    1,385.78x = 718,769.43
  5. Step 5: Solve for x
    x = 718,769.43/1,385.78
  6. Step 6: Final answer
    x = 518.67

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Double scale
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Similar ratio
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1.5x scale

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.