Home / 429.86-643.64-342.78

Finding the Fourth Proportional to 429.86, 643.64 and 342.78

Calculator

Solution

The fourth proportional to 429.86, 643.64 and 342.78 is: 513.25

Step by Step Solution

  1. Step 1: Write the proportion equation
    429.86 : 643.64 = 342.78 : x
  2. Step 2: Convert to fraction form
    429.86/643.64 = 342.78/x
  3. Step 3: Cross multiply
    429.86x = 643.64 × 342.78
  4. Step 4: Simplify right side
    429.86x = 220,625.21
  5. Step 5: Solve for x
    x = 220,625.21/429.86
  6. Step 6: Final answer
    x = 513.25

Related Problems

Find fourth proportional to 214.93, 321.82 and 171.39
Half scale
Find fourth proportional to 859.71, 1,287.27 and 685.56
Double scale
Find fourth proportional to 430.86, 645.13 and 343.78
Similar ratio
Find fourth proportional to 644.78, 965.45 and 514.17
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.