Answer:
2/3
Step-by-step explanation:
To add fractions add the numbers on top to each other and leave the bottom numbers alone if they are the same number.

Let:
x = Chemistry textbooks sold
y = Physics textbooks sold
The textbook store sold a combined total of 260, so:

The number of chemistry books sold was three times the number of physics textbooks sold, so:

Let:

Replace (2) into (1):

Replace the value of y into (2):
Answer:
The score that separates the lower 5% of the class from the rest of the class is 55.6.
Step-by-step explanation:
Problems of normally distributed samples can be solved using the z-score formula.
In a set with mean
and standard deviation
, the zscore of a measure X is given by:
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 pvalue, we get the probability that the value of the measure is greater than X.
In this question:

Find the score that separates the lower 5% of the class from the rest of the class.
This score is the 5th percentile, which is X when Z has a pvalue of 0.05. So it is X when Z = -1.645.


The score that separates the lower 5% of the class from the rest of the class is 55.6.
Okay, I understand. You found the correct answer. I won't get points. Sniffle.Sniffle.
Answer:
-7 , -5
Step-by-step explanation:
use the AC method, find two numbers that multiply to 35 and add to 12. those numbers are 7 and 5. then u have (m+7)(m+5), so m = -7,-5