1) 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.Sixty-twowind speed readings gave an average velocity ofx= 1075 cm/sec.Based on long-term experience,can be assumed to be275cm/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

2) Allen's hummingbird (Selasphorus sasin) has been studied by zoologist Bill Alther.Suppose a small group of19Allen's hummingbirds has been under study in Arizona. The average weight for these birds isx= 3.15 grams.Based on previous studies, we can assume that the weights of Allen's hummingbirds have a normal distribution, with=0.28gram.

(a) Find an 80% confidence interval for the average weights of Allen's hummingbirds in the study region. What is the margin of error? (Round your answers to two decimal places.)

lower limit=

upper limit=

margin of error=

(b) What conditions are necessary for your calculations? (Select all that apply.)

is known

normal distribution of weights

is unknown

nis large

uniform distribution of weights