Answer: the answer is -1
Step-by-step explanation:
Answer: 80 feet
Step-by-step explanation:
We can write these as fractions and do cross multiplication with the numerator being the height of the object while the denominator being the length of the shadow:
5 * 128 = 8x
640 = 8x
80 = x
Thus, the height of the lighthouse is 80 feet tall.
Remark
The way you have to set this up is to take the new number for the males and put it over the total for the males and females. The new number for the males / total = 3/5.
Step One
Find the total number of females
100 + 160 = 260 when 100 females have been added to the study.
Step Two
Find the number of males
The total number of males = 240 + x where x is the number of males to be added.
Step Three
Find the total for both
260 + 240 + x = Total
500 + x = Total.
Step Four
Find the ratio of males to total
(240 + x) / (500 + x) = 3/5
Step Five
Cross multiply and solve
(240 + x)*5 = (500+x)*3
1200 + 5x = 1500 + 3x Subtract 1200 from both sides.
5x = 1500 - 1200 + 3x
5x = 300 + 3x Subtract 3x from both sides.
5x - 3x = 300
2x = 300 Divide by 2
x = 300 / 2
x = 150
Check
(240 + 150 ) / (500 + 150) = ? 3/5
390 / 650 = ? 3/5
39/65 = ? 3/5 Divide the top and bottom on the left by 13
3/5 = 3/5 and it checks.
Answer:
b) -10
Step-by-step explanation:
x^2 + 3x + k = (x - 2)(x - a)
(x - 2)(x - a) = x^2 - 2x - ax + 2a = x^2 + [-2 - a)x] + 2a
-2 - a = 3
2a = k
a = -5
k = 2(-5) = -10
Answer: b) -10
