Home / 518.10-780.69-428.80

Finding the Fourth Proportional to 518.10, 780.69 and 428.80

Calculator

Solution

The fourth proportional to 518.10, 780.69 and 428.80 is: 646.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    518.10 : 780.69 = 428.80 : x
  2. Step 2: Convert to fraction form
    518.10/780.69 = 428.80/x
  3. Step 3: Cross multiply
    518.10x = 780.69 × 428.80
  4. Step 4: Simplify right side
    518.10x = 334,759.87
  5. Step 5: Solve for x
    x = 334,759.87/518.10
  6. Step 6: Final answer
    x = 646.13

Related Problems

Find fourth proportional to 259.05, 390.35 and 214.40
Half scale
Find fourth proportional to 1,036.20, 1,561.38 and 857.60
Double scale
Find fourth proportional to 519.10, 782.20 and 429.80
Similar ratio
Find fourth proportional to 777.15, 1,171.04 and 643.20
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.51) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.