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Finding the Fourth Proportional to 839.90, 1,259.66 and 319.72

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Solution

The fourth proportional to 839.90, 1,259.66 and 319.72 is: 479.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.90 : 1,259.66 = 319.72 : x
  2. Step 2: Convert to fraction form
    839.90/1,259.66 = 319.72/x
  3. Step 3: Cross multiply
    839.90x = 1,259.66 × 319.72
  4. Step 4: Simplify right side
    839.90x = 402,733.75
  5. Step 5: Solve for x
    x = 402,733.75/839.90
  6. Step 6: Final answer
    x = 479.50

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Double scale
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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.