A lightly reinforced $8-$in$.-$thick floor in an underground parking garage is supported along its

outside edges by a $20-$in$.-$thick basement wall. Cracks have developed in the slab perpendicular to

the basement wall at roughly $6$ ft on centers. The slab is $48$ months old and the wall is $50$ months

old. The concrete is $4,000$ psi, made from Type I cement, and was moist$-$cured for $5$ days for each

member. The average relative humidity is $60$ percent. Compute the width of these cracks, assuming

that they result from the basement wall restraining slab shrinkage parallel to the wall. Assume that:

$$ The slab spans $24$ ft in one direction and $12$ ft in the other direction.

$$ The edges of the slab are not exposed to the atmosphere.

$$ The portion of the wall under consideration is $10$ ft high and has a length of $24$ ft$.$

$$ The bottom and edges of the wall are continuous, and thus, not exposed to the atmosphere.