Transcript Math Contest 4/16

MATH CONTEST 4/16
MOWING LAWNS
Ron and Darrell mow lawns to earn money in the summer. Ron has a riding
mower. He charges $18 a yard and pays his little brother $7 to help. He is
able to do 9 yards in a day.
Darrell has a walking mower. He charges $20 a yard and does 8 yards a
day. Who do you think does better? Explain your answer.
MOWING LAWNS
ANSWER
• Ron charges $18 a yard but only clears $11 since he
pays his brother $7. Ron will make 9 x $11 a day so
clears $99. Darrell clears $20 a yard and though he
only completes 8 a day he makes 8 x $20 so clears
$160 a day. Darrell clearly is doing better.
TURKEY TIME
Julia Child was roasting a turkey. It has been out of the oven for 20 minutes.
The turkey was roasting for 4 hours and 15 minutes. The oven was
preheated for 10 minutes. If it is 5:00 now, then what time did Julia put the
turkey in the oven?
TURKEY TIME
ANSWER
• Count backwards! Start at 5:00 count back 20
minutes to 4:40. Count back 4 hours and 15 minutes
to 12:25. The time for preheating does not matter!
So the answer is 12:25!
JUMPING FROGS
A frog jumped on several stones on his way to the pond. He did not land
on the same stone twice. The product of all of the stones that he hopped
on was 19,635. On which stones did he jump?
JUMPING FROGS
ANSWER
• Think prime numbers!
• 3 x 5 x 7 x 11 x 17 = 19635.
MULTIPLICATION MADNESS
• Use multiplication to solve these arrays:
MULTIPLICATION MADNESS
ANSWER
BIRTHDAY BEACH BASH
Twins Maggie and Dana and their friend Rebecca were celebrating their
tenth birthdays with a party at the beach. The first fun activity was water
games. As Chelsea arrived, she observed that 1/3 of the kids were playing
with beach balls, 40% were exploring underwater with goggles, and .25 were
floating on tubes.
The party continued with many games, presents, and the ever popular cake
and ice cream. When the party was over, each kid received a party bag
and a balloon to take home. There were even 3 left for Maggie, Dana, and
Rebecca.
How many balloons were needed for the beach party?
BIRTHDAY BEACH BASH
ANSWER
• First convert - she observed that 1/3 of the kids were
playing with beach balls, 40% were exploring
underwater with goggles, and .25 were floating on tubes
to fractions. 1/3, 40% to 2/5 and .25 to 1/4. Next find the
lcd for the 3 fractions which is 3 x 5 x 4 = 60 so that you
can find the actual number of people who are
attending the party by writing fractions for each group.
Rewrite the fractions to 20/60, 24/60, and 15/60. If you
add the fractions you will get 59/60 and if you add 1/60
for Chelsea who observed the fractional makeup of
party activities you will get 60/60 people who were
asked to the party. If you add in the 3 for whom the
party was given you will see that 63 balloons were
needed.