Divide 2.25 by 1.50. That equals 1.5. That’s the equivalent to 50% because if you subtract 1 from 1.5 and multiply by 100. You get the same answer. Only do that for numbers greater than one, otherwise it won’t work
1 SD away from mean is 68% of data. 2 SD away from mean is 95% of data. 3 SD away from mean is 99.7% of data.
1 SD away: 190+30=220
2 SD away: 220+30=250
This shows we are on the outer 5 percent of the normal distribution. Since you said "more", that means we only look at the right side of your 5%, which is only 2.5%