The average body mass index of children 9 years old is 18.4 with a standard deviation of 4.5. If it is known that the distribution is approximately normal, what is the body mass index of a 9-year-old child at the 82nd percentile

Mass index for a 9-year-old child (at 82nd percentile ) = 22.51

Step-by-step explanation:

Given:

Mass index for a 9-year-old child  = 18.4

Standard deviation = 4.5

Find:

Mass index for a 9-year-old child (at 82nd percentile )

Computation:

At 82nd percentile,

p-value = 0.82

p-value from Z table score = 0.9153

Mass index for a 9-year-old child (at 82nd percentile ) = Mass index for a 9-year-old child + p-value from Z table score(Standard deviation)

Mass index for a 9-year-old child (at 82nd percentile ) = 18.4 + 0.9153(4.5)

Mass index for a 9-year-old child (at 82nd percentile ) = 18.4 + 4.11

Mass index for a 9-year-old child (at 82nd percentile ) = 22.51

0.305

Step-by-step explanation:

When we use the percentage (%) notation, to express for example the happening of a success is X%, we are expressing that the corresponding fact is happening X times every 100 times. Instead of X% we could use X/100.

In this example, every 100 units of his payment check, Landon takes 30,5 unites and puts them to his saving account. So, instead  of 30.5% we could say 30.5/100. (30.5% = 30.5/100).

So, we have:

30.5% = 30.5/100 = 0.305

This way, 0.305 is the decimal equivalent to 30.5%.

Observation: For avoiding comas in the latter fraction we could also say: 305/1000.