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.

intensity of the vector is v= √37 ≈ 6.08 units and make angle ∡α ≈ 9.46° with east direction

step-by-step explanation:

required vector is consists of the two componentsvx= 2+4=6 units   and vy= 1 unit and vx ⊥ vywe will use pythagorian theorem to find intensity of the vector vv∧2 = vx∧2 + vy∧2 => v = √vx∧2 + vy∧2 = √6∧2 + 1∧2 = √36+1 = √37 ≈ 6.08 unitsthe angle ∡α between vector and east direction we wil find with tanαtanα = 1/6 => α = arc tanα = arc 1/6 => α ≈ 9.46°

hope this

1e+27

step-by-step explanation: