The phrase "a certain rate and" is correct and usable in written English.
It can be used when discussing a specific rate in a context that requires further elaboration or continuation of the thought.
Example: "The project will be funded at a certain rate and will require additional resources to meet the deadlines."
Alternatives: "a specific rate and" or "an established rate and".
I work and think at a certain rate and expect everyone to be the same.
Cells in primary auditory cortex respond preferably to frequency sweeps of a certain rate and direction.
Every time you pull this particular carbon trigger at a certain rate and dump it into the atmosphere, that's what you get.
Bowlers it seems have simply got used to sending down their overs at a certain rate and to alter that would be like breaking into a sprint having trained at a jog.
The basic approach to doing this is to consider the kiln as a furnace system composed of a control volume with well-defined spatial boundaries into which mass and energy enter at a certain rate and leave at another rate.
"Then he told us that we have our own inner clock, and it ticks at a certain rate, and you're going to get to certain places at times different than everyone else is, but that doesn't make you any less of a musician".
In model 2 (4), cases are detected at a certain rate (patient diagnostic rate), and the patients die or self-cure at a certain rate.
Banks collect deposits in return for paying a certain rate of interest, and they use the deposits to make loans at a higher rate.
You're going to pay us a certain rate of return, and if there's anything left we'll split it".
You borrow a certain amount of money at a certain rate of interest and pay it back in a certain amount of time.
Indeed, high levels of aneuploidy are associated with increased adaptability in plants and yeast, and a certain rate of aneuploidy, leading to precise percentages of mosaic aneuploidy, is common in several mammals' embryos (see van Soom & Boerjan chapter 10), including humans.
