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3 years ago

Nibbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb

Mathematics

1 answer:

Vera_Pavlovna [14]3 years ago

4 0

Answer:

Yeah I would say the correct answer would already be that

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How do I solve part b and c

OLEGan [10]

Answer:

part a: 52%

part b: 0.4

part c: 0.24

Step-by-step explanation:

For part one, you find the frequency of the number of people that are less that 20. You add the number of tics in each bar and you divide by the total.

so for part a it is (7+6+9+4)/ (7+6+9+4+4+12+8)

for part b you add up the values that are greater than 25(less than 35)

(12+8)/total

part c you find the number of people between 25 and 30

that's 12

over total

12/total

4 0

3 years ago

Use a whole number, a fraction, one plus sign, and four 2's to make 23.

alexira [117]

22+2/2=23

22 is whole number
one plus sign
and 2/2 is the fraction
4 digits are 2

6 0

3 years ago

A math professor notices that scores from a recent exam are normally distributed with a mean of 61 and a standard deviation of 8

Alexeev081 [22]

Answer:

a) 25% of the students exam scores fall below 55.6.

b) The minimum score for an A is 84.68.

Step-by-step explanation:

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Mean of 61 and a standard deviation of 8.

This means that $\mu = 61, \sigma = 8$

(a) What score do 25% of the students exam scores fall below?

Below the 25th percentile, which is X when Z has a p-value of 0.25, that is, X when Z = -0.675.

$Z = \frac{X - \mu}{\sigma}$

$-0.675 = \frac{X - 61}{8}$

$X - 61 = -0.675*8$

$X = 55.6$

25% of the students exam scores fall below 55.6.

(b) Suppose the professor decides to grade on a curve. If the professor wants 0.15% of the students to get an A, what is the minimum score for an A?

This is the 100 - 0.15 = 99.85th percentile, which is X when Z has a p-value of 0.9985. So X when Z = 2.96.

$Z = \frac{X - \mu}{\sigma}$

$2.96 = \frac{X - 61}{8}$