Two square foundations $(1$ m by $1$ m $)$ are built adjacent to each other with a spacing of $0\mathrm{.}25$

m as shown in the below figure. The foundations support a stress of $100$ kPa each. Calculate

the vertical stress increase in a soil element located midway between the foundations and at a

depth of $1$ m $.$ To reduce the stresses on the same element by a factor of $10,$ what distance

would you recommend the foundations are placed?