Correct answer only !

use technology or a z-distribution table to find the indicated area.

suppose the distances from the center of a target that arrows strikes are normally distributed with a mean of 20 cm and a standard deviation of 6.4 cm.

approximately 25% of the arrows are further than what distance from the center?

 b) 15.7

Step-by-step explanation:

Look at the z-table (below) to find 0.2500  

Notice that the value is not on the table but is between 0.2486 and 0.2517 which are located on the z-table at 0.67 and 0.68

The given value is closer to 0.2486 so use 0.67 as the z-score.

Now, let's find the x-value using the formula:

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)