Home / 890.39-1,335.87-428.20

Finding the Fourth Proportional to 890.39, 1,335.87 and 428.20

Calculator

Solution

The fourth proportional to 890.39, 1,335.87 and 428.20 is: 642.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    890.39 : 1,335.87 = 428.20 : x
  2. Step 2: Convert to fraction form
    890.39/1,335.87 = 428.20/x
  3. Step 3: Cross multiply
    890.39x = 1,335.87 × 428.20
  4. Step 4: Simplify right side
    890.39x = 572,019.53
  5. Step 5: Solve for x
    x = 572,019.53/890.39
  6. Step 6: Final answer
    x = 642.44

Related Problems

Find fourth proportional to 445.20, 667.94 and 214.10
Half scale
Find fourth proportional to 1,780.78, 2,671.74 and 856.40
Double scale
Find fourth proportional to 891.39, 1,337.37 and 429.20
Similar ratio
Find fourth proportional to 1,335.59, 2,003.81 and 642.30
1.5x scale

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.