This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.
Q: The city has numerous neighborhoods consisting of vacant properties resulting in low inhabited density in those areas, stretching city services and infrastructure. These neighborhoods are concentrated in the northeast and on the city's fringes. A 2009 parcel survey found about a quarter of residential lots in the city to be undeveloped or vacant, and about 10% of the city's housing to be unoccupied. The survey also reported that most (86%) of the city's homes are in good condition with a minority (9%) in fair condition needing only minor repairs.
A:
How many of Detroit's residential lots are are underdeveloped?