First we need to multiply to make the fractions have equal denominators so we can add/subtract.
math: 1/3 x 4/4=4/12
science: 1/4 x 3/3=3/12
Now we can find the time she spent on history (I assume this is what you are looking for)
Total time-math time<span>-science time=history time</span>
12/12-4/12-3/12
=5/12
Amy spent 5/12 of her time working on history.
The factor pairs of a number when multiplied give the original number.
Therefore, all the factor pairs of 28 are:

The correct choice is the first one
(a) P(X < 3) = P(X = 0) + P(X = 1) + P(X = 2) = 0.11 + 0.52 + 0.19 = 0.82
(b) P(X ≥ 1) = P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4) = 0.52 + 0.19 + 0.12 + 0.06 = 0.89
(c) µ = 0×0.11 + 1×0.52 + 2×0.19 + 3×0.12 + 4×0.06 = 1.5
(d) σ² = (0²×0.11 + 1²×0.52 + 2²×0.19 + 3²×0.12 + 4²×0.06) - µ² = 1.07
σ = √(σ²) ≈ 1.03
The answer in the attached figure
Step-by-step explanation:
To change from exponential form to logarithmic form, identify the base of the exponential equation and move the base to the other side of the equal sign and add the word “log”. Do not move anything but the base, the other numbers or variables will not change sides.
this is pdf for more explain : Changing from Exponential to Logarithmic Form (link text )