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Finding the Fourth Proportional to 1,386.81, 2,079.95 and 947.79

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Solution

The fourth proportional to 1,386.81, 2,079.95 and 947.79 is: 1,421.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,386.81 : 2,079.95 = 947.79 : x
  2. Step 2: Convert to fraction form
    1,386.81/2,079.95 = 947.79/x
  3. Step 3: Cross multiply
    1,386.81x = 2,079.95 × 947.79
  4. Step 4: Simplify right side
    1,386.81x = 1,971,351.07
  5. Step 5: Solve for x
    x = 1,971,351.07/1,386.81
  6. Step 6: Final answer
    x = 1,421.50

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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.