The mean midday temperature recorded in june in a city in south california is 36ºc, and the standard deviation is 3ºc. assuming the data is normally distributed, the number of days in june when the midday temperature was between 39ºc and 42ºc is
a) 3
b) 4
c) 7
d) 12

The mean is : 36°.
The standard deviation ( SD ) is: 3°
36° + 1 SD = 36° + 3° = 39°
36 + 2 SD = 36° + 2 * 3° = 36° + 6° = 42°
Between 39° and 42° is 13.5% days ( and there are 30 days in June ).
30 * 0.135 = 4.05 ≈ 4

B ) 4

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.