We take a sample of 94 ultraluminous, optical quasars from the search of over
14,486 deg^2 by Onken et al. 2022 in the range 4.4<redshift<5.2 and match them
against the Rapid ASKAP Continuum Survey (RACS) observed on the Australian
Square Kilometre Array Pathfinder (ASKAP). From this most complete sample of
the bright end of the redshift ~5 quasar luminosity function, there are 10
radio continuum detections of which 8 are considered radio-loud quasars. The
radio-loud fraction for this sample is 8.5 \pm 2.9 per cent. Jiang et al. 2007
found that there is a decrease in the radio-loud fraction of quasars with
increasing redshift and an increase with increasing absolute magnitude at rest
frame 2500 Angstroms. We show that the radio-loud fraction of our quasar sample
is consistent with that predicted by Jiang et al. 2007, extending their result
to higher redshifts.Comment: Accepted by MNRA