Final answer:
The z-score with an area of 0.8600 to its right under the standard normal curve is approximately -1.08.
Step-by-step explanation:
To find the z-score with an area of 0.8600 to its right under the standard normal curve, we can use the z-table.
The z-table shows that the area to the left of a z-score with an absolute value of 1.08 is 0.85887, which means the area to the right is approximately 1 - 0.85887 = 0.14113.
Since we want the area to the right to be 0.8600, we need to find a z-score that has an area of approximately 0.14113 to the right. Looking up this area in the z-table gives us a z-score of approximately -1.08.