Past exam of the mathematics course of the University of Cambridge / 2017 / iii / Paper 310 / 4 / d

Using the leading predictions just obtained givesThe quadratic and cubic monomial inflation potentials satisfy the quoted interval for the scalar spectral index, whereas the quartic model lies below its lower endpoint. All three exceed the quoted bound on the tensor-to-scalar ratio. ThusThis conclusion uses the exam's numerical bounds and the specified 60-e-fold endpoint convention, not a substitution of later observational constraints. Even a modest endpoint adjustment does not reduce the predicted $r$ by the roughly factor of two or more needed here.