Home / 378.91-522.57-305.20

Finding the Fourth Proportional to 378.91, 522.57 and 305.20

Calculator

Solution

The fourth proportional to 378.91, 522.57 and 305.20 is: 420.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    378.91 : 522.57 = 305.20 : x
  2. Step 2: Convert to fraction form
    378.91/522.57 = 305.20/x
  3. Step 3: Cross multiply
    378.91x = 522.57 × 305.20
  4. Step 4: Simplify right side
    378.91x = 159,488.36
  5. Step 5: Solve for x
    x = 159,488.36/378.91
  6. Step 6: Final answer
    x = 420.91

Related Problems

Find fourth proportional to 189.46, 261.29 and 152.60
Half scale
Find fourth proportional to 757.82, 1,045.14 and 610.40
Double scale
Find fourth proportional to 379.91, 523.95 and 306.20
Similar ratio
Find fourth proportional to 568.37, 783.86 and 457.80
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.