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let's assume a critical/flat universe. Ho=70 km/s/Mpc. I computed Boltzman law for energy (volume) density by integrating Planck's law p rad= alpha*T^4. alpha= 7.56*10^-15 ergs/cm^3/K^4 (Which I computed to be 7.56*10^-16 Joules/m^3/K^4)

I dont know where to begin with this question.. there's no other values provided . I'm supposed to somehow find out the redshift at which the universe switched from being radiation dominated to matter dominated (point of time at which radiation density is equal to mass density). and the temperature of the universe at that time .

I tried making a formula by putting radiation density formula= matter density formula ,, but there's not enough values given to compute it.

thanks!