How to calculate weighted average

[HEMH6]

Weihted Average

Write a C program to calculate and print the weighted average of a list of N
floating point number, using the formula

Xave = F1X1 + F2X2+...+ FnXn

where the F's are fractional weighting factors,

i.e. 0<=F1<1, and F1+F2+...+Fn=1

For example: F1=0.1 F2=0.2 F3=0.3 F4=0.4 for n=4 and the sum=1.0

(a) Assume that N=4, and that the N numbers are already available in an array.
Use as input the following array: float X[4]={1.2,2.4,3.6,4.8};

(b) Prompt the user to enter the four weights from the keyboard. the program
should print an error messaage if the weights are out of range.

(c) For the result, the program should print the data, weights and the weighted
average.

[D_C]

for(i = 0, i < 4, i++)
{
  do
  {
    // get floating point number input
  }  while // input is not within weight range
  F[i] = input;
  sum += input;
}
if(sum != 1.0)
  // throw a fit
else
{
  for(i = 0; i < 4, i++)
    xAve += (F[i]*X[i]);
  xAve /= 4;
  // output xAve
}