MS. Winkler surveyed her students in just one class with 30 students to see how many siblings each of them had. Here are the results Only child: 5
1 sibling: 7
2 siblings: 13
3 or more siblings: 5

If she were to survey all 140 of her students, predict how many total have just 1 sibling. (Round to the nearest whole number)

Answer choices:
a)33
b)30
c)42
d)2