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Finding the Fourth Proportional to 989.90, 1,484.86 and 412.78

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Solution

The fourth proportional to 989.90, 1,484.86 and 412.78 is: 619.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    989.90 : 1,484.86 = 412.78 : x
  2. Step 2: Convert to fraction form
    989.90/1,484.86 = 412.78/x
  3. Step 3: Cross multiply
    989.90x = 1,484.86 × 412.78
  4. Step 4: Simplify right side
    989.90x = 612,920.51
  5. Step 5: Solve for x
    x = 612,920.51/989.90
  6. Step 6: Final answer
    x = 619.17

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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.