Please help, I’m unsure how to do standard deviation so I’m very confused!

a. With an average/mean of 7 dreams, one standard deviation away from the mean corresponds to the interval [7 - 1.7, 7 + 1.7] = [5.3, 8.7]. So children within one standard deviation of the mean experience somewhere between 5 and 9 dreams. Two standard deviations from the mean refers to the interval [7 - 2 * 1.7, 7 + 2 * 1.7] = [3.6, 10.4]. So children in this range have between 3.6 and 10.4 dreams.

b. We already know that the interval [5.3, 8.7] is one standard deviation from the mean. If we assume the number of dreams is normally distributed with mean 7 and standard deviation 1.7, then we can apply the empirical rule (a.k.a. 68-95-99.7), which says that for any normal distribution, roughly 68% of the distribution falls within one standard deviation of the mean. So we can expect roughly 68% of the 4800 children to have between 5.3 and 8.7 dreams, or about 3264 students.

cut 138 centimeters off

step-by-step explanation:

250-112 = 138

, and

for

step-by-step explanation:

we can analyze the pattern at which the terms increase. let us denote , , , so that we can call

note the following:

the pattern: to get the next term value, we just add the next term number (e.g. 1st, 2nd, to the previous term value (term values are the given numbers in the question, 1, 3, 6, 10, 15,

from , to get to , we add

from , to get to , we add

etc.

we need to form a recursive formula, a formula that has the next term as a function of the previous term. so a possible recursive formula can be

, and for