The numbers of beads on 500 handcrafted bead necklaces follow a normal distribution whose mean is 24 beads and standard deviation is 4 beads. Which sentence most closely summarizes the data?

a. About 24 necklaces have more than 28 beads.
b. About 48 necklaces have more than 28 beads.
c. About 80 necklaces have more than 28 beads.
d. About 96 necklaces have more than 28 beads.

Question

The numbers of beads on 500 handcrafted bead necklaces follow a normal distribution whose mean is 24 beads and standard deviation is 4 beads. Which sentence most closely summarizes the data?

a. About 24 necklaces have more than 28 beads.
b. About 48 necklaces have more than 28 beads.
c. About 80 necklaces have more than 28 beads.
d. About 96 necklaces have more than 28 beads.

anonymous · Answer

First, find out what percent of things will be above the first standard deviation away

anonymous · Answer

You basically have a $z$ score of $1$ here. $$
z=\frac{x-\mu}{\sigma}=\frac{28-24}{4} = 1
$$

anonymous · Answer

http://www.wolframalpha.com/input/?i=z+score+1 Left tailed will be about $0.1587$ of all necklaces.

anonymous · Answer

So bascically $15.87\%$ of the $500$ necklaces will be above $28$ beads. http://www.wolframalpha.com/input/?i=15.87%25+of+500

anonymous · Answer

I don't understand what that means,

anonymous · Answer

"that"?