What percent of the children in class K have been to London?

1) The number of boys in class K is equal to the number of girls in class K.
Let Number of girls = number of boys = x;
Nothing related to number of children visited London is given
Insufficient

2) Among the children of class K, the number of girls that have been to London is equal to the number of boys that have been to London.
Let Number of girls Visited London = number of boys Visited London = y
But, we don't know the Actual number of students of exact value of number of students visited to London
Insufficient

1 and 2 together,
But, we don't know the Actual number of students of exact value of number of students visited to London
Insufficient

Option E is correct

Statement 1
The number of boys in the class K is equal to the number of girls in class K.
This means that the ratio of boys to girls in class k is equal but this is not enough to give us a definite answer, hence statement 1 is INSUFFICIENT.

Statement 2
Among the children of class K the number of girls that have been to London is equal to the number of boys that have been to London.
There is no information about the total number of students in class K, hence we cannot find the % of students that have been to London.

Combining statement 1 and 2 together
Total no of boys = Total number of girls
Let total number of boys = 50
50 boys = 50 girls
Total no of students in class K =100 boys and girls Since they are in the same ratio
no of girls that have been to London = no of boys that have been to London
If no of girls that have been to London =10
Then % of children in class K that have been to London = 20%
If no of girls that have been to London =5
Then % of children in the class K that have been to London = 10%
Information available is not enough to to get a specific percentage.
Both statement together are not SUFFICIENT.
$$answer\ is\ Option\ E$$