Solve the following questions.
1. Given that y and x are directly proportional and y=2 when x=5, find the value of y when x=15.
2. The number of gallons of fuel used in a trip varies directly with the number of miles traveled. If a trip of 270 miles required 12 gallons of fuel, how many gallons are required for a trip of 400 miles?
3. Karen earns 285 pesos for working six hours. If the amount she earned varies directly with the number of hours she works, how much will she earn if she works 10 hours?
4. A 150-ml bottle of food coloring costs 5.25 pesos. If the cost varies directly with the volume of juice, what should be the cost of a 250-ml bottle of food coloring?
5. An egg is dropped form the rooftop. The distance it falls varies directly with the square of the time it falls. It takes 0.5 seconds for the egg to fall 8 feet. How long will it take the egg to fall form the height of 200 feet?
Answers & Comments
Answer:
1. y=6
2.
gallons
3. Php475
4. Php 8.75
5.
seconds
Step-by-step explanation:
1. y=kx
First:
Given: y= 2 y=kx
x= 5 2= k(5)
k=?
= ![\frac{k5}{5} \frac{k5}{5}](https://tex.z-dn.net/?f=%5Cfrac%7Bk5%7D%7B5%7D)
k=![\frac{2}{5} \frac{2}{5}](https://tex.z-dn.net/?f=%5Cfrac%7B2%7D%7B5%7D)
2nd: Given k =
y=kx
x= 15 y=(
) (15)
y=? y= 6
2. Let g= the number of gallons
d= miles travelled
g is directly proportional to d (g=kd)
1st, Given: Solution:
d= 270 miles g=kd
g= 12 gallons 12= k(270)
k=?
= ![\frac{k270}{270} \frac{k270}{270}](https://tex.z-dn.net/?f=%5Cfrac%7Bk270%7D%7B270%7D)
k=![\frac{12}{270} \frac{12}{270}](https://tex.z-dn.net/?f=%5Cfrac%7B12%7D%7B270%7D)
2nd, Given: Solution:
k=
g=kd
d= 400 miles g=(
) (400)
g=? g=
or ![\frac{160}{9} \frac{160}{9}](https://tex.z-dn.net/?f=%5Cfrac%7B160%7D%7B9%7D)
3. Let a= amount earned
t=number of hours
a is varies directly with t (a=kt)
1st, Given: Solution:
a= P285 a=kt
t= 6 hours 285= k(6)
k=?
= ![\frac{k(6)}{6} \frac{k(6)}{6}](https://tex.z-dn.net/?f=%5Cfrac%7Bk%286%29%7D%7B6%7D)
k=
or ![\frac{95}{2} \frac{95}{2}](https://tex.z-dn.net/?f=%5Cfrac%7B95%7D%7B2%7D)
2nd, Given: Solution:
t= 10 hours a=kt
k=
a=(
)(10)
a=? a=P475
4. Let b= the volume of food coloring bottle
c= cost of food coloring bottle
c varies directly with b ( c=kb)
1st, Given: b= 150 mL Solution:
c= Php 5.25 c=kb
k= ? 5.25=k (150)
k =
or ![\frac{7}{200} \frac{7}{200}](https://tex.z-dn.net/?f=%5Cfrac%7B7%7D%7B200%7D)
2nd, Given: Solution:
b=250 mL c=kb
k=
c=(
)(250)
c=? c=
or
or Php 8.75
5. Let d= distance
d is varies directly with the
(d=k
)
1st, Given: Solution:
d=8 feet d=k![t^{2} t^{2}](https://tex.z-dn.net/?f=t%5E%7B2%7D)
t =0.5 seconds 8= k (
)
k= ? 8= k(0.25)
k=
or 32
2nd, Given: Solution:
d=200 feet d=k
k =32 200= 32
t = ?
= ![\frac{32t^{2} }{32} \frac{32t^{2} }{32}](https://tex.z-dn.net/?f=%5Cfrac%7B32t%5E%7B2%7D%20%7D%7B32%7D)