Home / 790.47-1,087.38-642.78

Finding the Fourth Proportional to 790.47, 1,087.38 and 642.78

Calculator

Solution

The fourth proportional to 790.47, 1,087.38 and 642.78 is: 884.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    790.47 : 1,087.38 = 642.78 : x
  2. Step 2: Convert to fraction form
    790.47/1,087.38 = 642.78/x
  3. Step 3: Cross multiply
    790.47x = 1,087.38 × 642.78
  4. Step 4: Simplify right side
    790.47x = 698,946.12
  5. Step 5: Solve for x
    x = 698,946.12/790.47
  6. Step 6: Final answer
    x = 884.22

Related Problems

Find fourth proportional to 395.24, 543.69 and 321.39
Half scale
Find fourth proportional to 1,580.94, 2,174.76 and 1,285.56
Double scale
Find fourth proportional to 791.47, 1,088.76 and 643.78
Similar ratio
Find fourth proportional to 1,185.71, 1,631.07 and 964.17
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.