Propranolol binds to -adrenergic receptors with a KI of 8.9 10-9 M. What concentration of propranolol

Propranolol binds to β-adrenergic receptors with a KI of 8.9 × 10-9 M. What concentration of propranolol would be required to achieve a 50% reduction in the binding of the receptor agonist isoproterenol if the agonist concentration is 10 nM and its dissociation constant for the receptor is 4.8 × 10-8 M?