We have a standard distribution with a men of 266 and a standard deviation of 12. We are asked to find the probability that x is larger than or equal to 254.
Notice that 266 minus 12 is exactly 254 . That is, we are asked to find the probability of x larger than or equal to a location of one standard deviation below the mean and all the way up to infinity.
Recall as well that half of the normal distribution corresponds to 50% probability. (this is the half to the right of the mean.
To this 50% probability we need to add the probability of x being between one standard deviation to the left and the mean. This part is about 34.1 %
so the total probability would be: 50% + 34.1% = 84.1 percent
Recall that 84.1 percent in decimal form is written as: 0.841.
Therefore the correct answer to choose is answer C