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Finding the Fourth Proportional to 1,239.71, 1,712.58 and 990.70

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Solution

The fourth proportional to 1,239.71, 1,712.58 and 990.70 is: 1,368.59

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,239.71 : 1,712.58 = 990.70 : x
  2. Step 2: Convert to fraction form
    1,239.71/1,712.58 = 990.70/x
  3. Step 3: Cross multiply
    1,239.71x = 1,712.58 × 990.70
  4. Step 4: Simplify right side
    1,239.71x = 1,696,653.01
  5. Step 5: Solve for x
    x = 1,696,653.01/1,239.71
  6. Step 6: Final answer
    x = 1,368.59

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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.