To find the ratio of boys to all children, first, you need to determine the total number of children in the group.
Total number of children = Number of boys + Number of girls
Total number of children = 7 boys + 90 girls = 97 children.
Now, to find the ratio of boys to all children:
Ratio of boys to all children = Number of boys : Total number of children
Ratio of boys to all children = 7 : 97.
So, the ratio of boys to all children is 7:97.