The amount of growth, in 15-day period, for population of sunflower plants was found to follow normal distribution with mean 3.18 cm as well as standard deviation 0.53cm. What percentage of plants grow
a) 4 cm or more?
b) 3 cm or less?
c) Between 2.5 and 3.5 cm?
d) In what range do the middle 90% of all growth values lie?
e) For the sunflower growth distribution, what is the 25th percentile?