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Finding the Fourth Proportional to 1,315.60, 1,971.90 and 989.92

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Solution

The fourth proportional to 1,315.60, 1,971.90 and 989.92 is: 1,483.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,315.60 : 1,971.90 = 989.92 : x
  2. Step 2: Convert to fraction form
    1,315.60/1,971.90 = 989.92/x
  3. Step 3: Cross multiply
    1,315.60x = 1,971.90 × 989.92
  4. Step 4: Simplify right side
    1,315.60x = 1,952,023.25
  5. Step 5: Solve for x
    x = 1,952,023.25/1,315.60
  6. Step 6: Final answer
    x = 1,483.75

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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.