my_list = [("45", "Jane"), ("11", "Will"), ("37.68", "86.78"), ("Rob", "89.90")]

print("The list is : ")
print(my_list)

my_result = []
for tup in my_list:
    temp_val = []
    for elem in tup:
        if elem.isalpha():
            temp_val.append(elem)
        else:
            temp_val.append(float(elem))
    my_result.append((temp_val[0],temp_val[1]))

print("The float values are : " )
print(my_result)

The list is :
[('45', 'Jane'), ('11', 'Will'), ('37.68', '86.78'), ('Rob', '89.90')]
The float values are :
[(45.0, 'Jane'), (11.0, 'Will'), (37.68, 86.78), ('Rob', 89.9)]