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Finding the Fourth Proportional to 638.76, 881.34 and 390.18

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Solution

The fourth proportional to 638.76, 881.34 and 390.18 is: 538.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.76 : 881.34 = 390.18 : x
  2. Step 2: Convert to fraction form
    638.76/881.34 = 390.18/x
  3. Step 3: Cross multiply
    638.76x = 881.34 × 390.18
  4. Step 4: Simplify right side
    638.76x = 343,881.24
  5. Step 5: Solve for x
    x = 343,881.24/638.76
  6. Step 6: Final answer
    x = 538.36

Related Problems

Find fourth proportional to 319.38, 440.67 and 195.09
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Double scale
Find fourth proportional to 639.76, 882.72 and 391.18
Similar ratio
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1.5x scale

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.