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Finding the Fourth Proportional to 1,391.68, 1,921 and 802.45

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Solution

The fourth proportional to 1,391.68, 1,921 and 802.45 is: 1,107.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,391.68 : 1,921 = 802.45 : x
  2. Step 2: Convert to fraction form
    1,391.68/1,921 = 802.45/x
  3. Step 3: Cross multiply
    1,391.68x = 1,921 × 802.45
  4. Step 4: Simplify right side
    1,391.68x = 1,541,506.45
  5. Step 5: Solve for x
    x = 1,541,506.45/1,391.68
  6. Step 6: Final answer
    x = 1,107.66

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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.