7th Grade Challenging Math

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7-61) Jenny is 64 inches tall. She is standing next to a lamp post on a sunny afternoon. Her shadow is 4 feet long. At the same time shadow of the lamp post is 10 ft long. How tall is the lamp post? (1 foot is 12 inches.)

7-62) The small square is 100 square cm. What is the area of the large square?

7-63) The small square is 100 square cm. What is the area of the purple part?

7-64) Max has some spiders and iguanas. There are 20 heads and 104 legs in all. How many spiders and iguanas are there?  Spiders have 8 legs.

7-65) It takes 4 workers 3 days to assemble 360 car seats. How long does it take 3 workers to assemble 900 car seats? Assume all workers assemble car seats at the same speed.

7-66) Mario has 3 red marbles and 3 blue marbles in a box. He picks two marbles randomly without looking.
a) What is the probability that both marbles are red?
b) What is the probability that both marbles are the same color?
c) What is the probability that he picks one blue and one red?

7-67) Jim has 3 red marbles and 3 blue marbles in a box. Jim picks three marbles randomly without looking.
a) What is the probability that he picks all 3 blues?
b) What is the probability that he picks all 3 of the same color?

7-68) Jane flips a coin 5 times.
What is the chance she will get all five heads?

7-69) Multiple choice problem:

What is the approximate value of 1/2 + 1/4 + 1/8 + 1/16 + 1/32 + 1/64 + 1/128 + ......

a) 2;  b) 3;  c) 1;  d) 1.5

7-70) Tom flips a coin 3 times.
(a) What is the chance that he will get 2 heads?
(b) What is the chance that he will get at least two heads?
(c) What is the chance he will get at least 1 head?
 

More challenging math problems for seventh grade:
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71-80  81-90