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Finding the Fourth Proportional to 1,689.90, 2,332.30 and 991.28

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Solution

The fourth proportional to 1,689.90, 2,332.30 and 991.28 is: 1,368.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,689.90 : 2,332.30 = 991.28 : x
  2. Step 2: Convert to fraction form
    1,689.90/2,332.30 = 991.28/x
  3. Step 3: Cross multiply
    1,689.90x = 2,332.30 × 991.28
  4. Step 4: Simplify right side
    1,689.90x = 2,311,962.34
  5. Step 5: Solve for x
    x = 2,311,962.34/1,689.90
  6. Step 6: Final answer
    x = 1,368.11

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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.