Life span of platelets is:
120 days
10 days
30 days
60 days
Platelets are small, granulated bodies that aggregate at sites of vascular injury. They lack nuclei and are 2–4 μm in diameter. There are about 300,000/μL of circulating blood, and they normally have a half-life of about 4 days. The megakaryocytes, giant cells in the bone marrow, form platelets by pinching off bits of cytoplasm and extruding them into the circulation.
Life span of platelets is around 8-10  days.
Reference: Ganong’s Review of Medical Physiology T W E N T Y - F I F T H   E D I T I O N page no 555