HELP QUICK IM FAILING Select the expression that represents the following statement: 6 times one fifth the sum of 13 and 7. (4 points)

a
6 x one fifth x (13 ÷ 7)

b
one fifth x (13 − 7) x 6

c
6 x one fifth x (13 x 7)

d
one fifth x (13 + 7) x 6

At wind speeds above 1000 centimeters per second (cm/sec), significant sand-moving events begin to occur. wind speeds below 1000 cm/sec deposit sand and wind speeds above 1000 cm/sec move sand to new locations. the cyclic nature of wind and moving sand determines the shape and location of large dunes. at a test site, the prevailing direction of the wind did not change noticeably. however, the velocity did change. fifty-nine wind speed readings gave an average velocity of x = 1075 cm/sec. based on long-term experience, σ can be assumed to be 245 cm/sec. (a) find a 95% confidence interval for the population mean wind speed at this site. (round your answers to the nearest whole number.) lower limit cm/sec upper limit cm/sec