The phrase "a certain number of classes" is correct and usable in written English.
It can be used when referring to an unspecified quantity of classes, often in an academic or organizational context.
Example: "The curriculum requires students to complete a certain number of classes to graduate."
Alternatives: "a specific number of classes" or "an unspecified number of classes."
Instead of letting users buy a certain number of classes each month, ClassPass is now selling credits that can go toward buying classes, allowing for a dynamic pricing model.
Today the packages are sold on a subscription basis, and instead of users being able to book a certain number of classes a month, they are now given between 25 and 100 credits instead.
For this, we pick a certain number of classes to be created, and then the data are distributed equally between the classes resulting into equal numbers of grid cells in each class [9, 34].
The Winter of 2012 was a bleak one, but Payal had been thinking for a while about a Passport product that would let people buy a certain number of classes per month and work as a loyalty tool for gyms and studios.
It's also usually the case that schools require students to take a certain number of classes in their major at their graduating institution; so if you take too many at your first college, they may not all transfer.
Others stated that "the majority" of subjects completed a certain number of classes or that there was a natural break in the data at a certain number of classes.
The unitisation system was also effective in that it achieved some reduction in capacity and effort in its application through the boat-replacement policy (based on Class-A and Class-B units) as it resulted in a certain number of Class-A and Class-B units being forfeited as new boats were built.
A classification problem is the following [ 33]: given a set of training instances, each described with a set of n attributes and each belonging to exactly one of a certain number of possible classes, learn to classify new, unseen objects.
The partitioning of the data across the 3 categories shows a good consensus on a certain number of sounds for each class.
Hence, there is a need to intelligently control the resource allocation and only allow a certain number of users in each class through admission control while taking advantage of best available channel conditions.
In particular, one-versus-all strategy are combined with SIP-FS to select feature types (each contains a certain number of features) for a specific class.
