The size of the left upper chamber of the heart is one measureof cardiovascular health. When the upper left chamber is enlarged,the risk of heart problems is increased. A paper described a studyin which the left atrial size was measured for a large number ofchildren age 5 to 15 years. Based on this data, the authorsconcluded that for healthy children, left atrial diameter wasapproximately normally distributed with a mean of 26.7 mm and astandard deviation of 4.7 mm.
(a)
Approximately what proportion of healthy children have leftatrial diameters less than 24 mm? (Round your answer to fourdecimal places.)
(b)
Approximately what proportion of healthy children have leftatrial diameters greater than 32 mm? (Round your answer to fourdecimal places.)
(c)
Approximately what proportion of healthy children have leftatrial diameters between 25 and 30 mm? (Round your answer to fourdecimal places.)
(d)
For healthy children, what is the value for which only about 20%have a larger left atrial diameter? (Round your answer to twodecimal places.)
mm
