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Finding the Fourth Proportional to 978.09, 1,348.75 and 646.09

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Solution

The fourth proportional to 978.09, 1,348.75 and 646.09 is: 890.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.09 : 1,348.75 = 646.09 : x
  2. Step 2: Convert to fraction form
    978.09/1,348.75 = 646.09/x
  3. Step 3: Cross multiply
    978.09x = 1,348.75 × 646.09
  4. Step 4: Simplify right side
    978.09x = 871,413.89
  5. Step 5: Solve for x
    x = 871,413.89/978.09
  6. Step 6: Final answer
    x = 890.93

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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.