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Finding the Fourth Proportional to 1,239.40, 1,709.54 and 977

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Solution

The fourth proportional to 1,239.40, 1,709.54 and 977 is: 1,347.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.40 : 1,709.54 = 977 : x
  2. Step 2: Convert to fraction form
    1,239.40/1,709.54 = 977/x
  3. Step 3: Cross multiply
    1,239.40x = 1,709.54 × 977
  4. Step 4: Simplify right side
    1,239.40x = 1,670,220.58
  5. Step 5: Solve for x
    x = 1,670,220.58/1,239.40
  6. Step 6: Final answer
    x = 1,347.60

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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.