To answer this, we need to assume a particular distribution, so let’s use the binomial distribution with p as the probability and n as the number of trials=4.
The mean is np and the variance is np(1-p). So np=4*0.95=3.80 in Japan and 4*0.60=2.40 in the US.
The variances are 3.80*0.05=0.19 in Japan and 2.40*0.4=0.96 in US.
The standard deviations are the square roots of the variances: 0.44 in Japan and 0.98 in US.
Japan: 3.80±0.44, US: 2.40±0.98