Consider the following two scenarios: 1. the mean height of coastal redwood trees is known to be 200 feet. in order to test whether a community of coastal trees were growing to be healthy in a park with high rates of tourism, a random sample of 20 trees were measured. it was found that for the 20 sampled trees, the average height was 197.5 feet with a standard deviation of 6.7. it is known that tree heights follow a normal distribution. 2. the mean height of coastal redwood trees is known to be 200 feet. in order to test whether a community of coastal trees were growing to be healthy in a park with high rates of tourism, a random sample of 20 trees were measured. it was found that for the 20 sampled trees, the average height was 197.5 feet. it is known that tree heights follow a normal distribution with a standard deviation of 7. which of the following is correct: a. in the second scenario, the population standard deviation is not known, therefore a z-test should be used. b. in the second scenario, the sample standard deviation is known, therefore a z- test should be used. c. in the second scenario, the population standard deviation is known, thereforea t-test should be used. d. in the second scenario, the population standard deviation is known, therefore a z-test should be used.

mr. flanders’ class sold 47 doughnuts and   mr. rodriquez’s class sold 38 cartons of milk

step-by-step explanation:

let x be the number of doughnuts sold by mr. flanders’ class and y be the number of cartons sold by mr. rodriquez’s class.

1. together, the classes sold 85 items, then

x+y=85.

2. both classes earn earned $104.49 for their school. if doughnuts were sold for $1.35 each, then x doughnuts costed $1.35x. if cartons of milk were sold for $1.08 each, then y cartons costed $1.08y. hence,

1.35x+1.08y=104.49.

3. solve the system of two equations:

if gloria has "carry over" minutes, (that is, any minutes paid for but not used in a month can be applied to her payment for minutes in the next month,) her total usage for the three months is: total minutes = 320 + 243 + 489 = 1052 minutes number of 200 minute blocks = 1052/200 = 5 r52 (that is 5 with a remainder of 52) rounding up the number of 200 minute blocks gives her usage for the three months as 6 blocks. the cost for six blocks is 6 x $25 = $150 she also has 200 - 52 or 148 carry over minutes if gloria pays each month and unused minutes are lost, applying the rounding up procedure to each month gives: first month usage of 320 minutes rounds up to 2 blocks of 200 minutes for a payment of 2 x $25 = $50 second month usage of 243 minutes rounds up to 2 blocks of 200 minutes for a payment of 2 x $25 = $50 third month usage of 489 minutes rounds up to 3 blocks of 200 minutes for a payment of 3 x $25 = $75 total payments for the three months are $50 + $50 + $75 = $175 get the plan with carry over minutes!

two? xd

step-by-step explanation: