If it is a single carriageway, then the speed limit will be 60mph, unless it states otherwise or there are legal enforcements in place (e.g. roadworks/speed restrictions.)
the answer is 30mph
This is a Ditloid. The answer is, 70 = National Speed Limit on a Dual Carriageway.
They don't ! Maximum speed on a dual carriageway is 60mph - Motorways is 70mph.
Unless specifically stated by a sign, the speed limits for cars are: Motorway: 70 MPH Dual Carriageway: 70 MPH Single Carriageway: 60 MPH Built up areas: 30 MPH (in towns, villages etc) Other vehicle types such as trucks and buses have their own speed limits.
If your on public roads you can drive at any speed up to the speed limit for the road your on provided it is safe to do so. In the UK the fastest speed limit is 70 mph on most motorways and duel carriageway's.
The maximum speed limit in a rural area can vary by location and country. In the United States, for example, it is typically around 55-70 mph on rural highways and interstates. It is important to be aware of and follow the posted speed limit signs in the area you are driving.
On a dual carraigeway with National Speed limit signs (a white circle with a diagonal black stripe) the limit for cars and commercial vehicles up to 7.5 Tonnes is 70 mph. There are lots of conditions that apply to this statement, so don't expect this answer to cover all possibilities.
Whatever the posted speed limit is.
There are several Interstate Highways with a 75 MPH speed limit at various points throughout their span, but there isn't one which has that speed limit at every single point.
Unless signs say otherwise, there are three speed limits for cars without trailers or caravans;- 30mph where there are streetlights. 60mph on single carriageway roads without streetlights. 70mph on motorways and duel carriageways without streetlights .
60mph unless slower speed limits are in force.