7th Grade Challenging Math

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7-51) Jenny mixes 2000 grams of sugar water which has a sugar content of 10%. Several days later, the sugar content is 20%. What is the weight of the sugar water now?
 

7-52) Adam mixes 1800 kg of salt water which has a salt content of 10%. Several days later, the salt content is 15%. What is the weight of the salt water now?
 

7-53) A farm has chickens, turkeys, rabbits and pigs. There are 60 pigs in all. The ratio of chickens versus the sum of the other 3 animals is 1/4. The ratio of turkeys versus the sum of the other 3 animals is 2/13. The ratio of rabbits versus the sum of the other 3 animals is 4/11. How many animals in all are there on the farm?
 

7-54) List the following fractions from the smallest to the largest (left to right).

2015/2016; 2016/2017, 2017/2018
 

7-55) Calculate

(1+1/9)*(1+1/8)*(1+1/7)*(1+1/6)*(1+1/5)*(1+1/4)*(1+1/3)*(1+1/2)

7-56) Calculate

(1-2/9)*(1-2/8)*(1-2/7)*(1-2/6)*(1-2/5)*(1-2/4)*(1-2/3)

 

7-57) When 391 is divided by a two digit number, the remainder is 6. How many such two digit numbers exist?
 

7-58) When 265 is divided by a two digit number, the remainder is 5. How many such two digit numbers exist?

7-59) Jefferson School has a math club and a science club. The ratio of students in these
two clubs is 4:5 (math : science). If 10 students from the science club moved to the math club, then the two clubs have same number of students. How many students are there in both clubs initially?

7-60) Matthew is 5 feet tall. He is standing next to a flag post on a sunny day. Matthew's shadow is 3 feet long. At the same time, the shadow of the flag post is 15 feet long. How tall is the flag post? (1 foot is 12 inches.)

More challenging math problems for seventh grade:
1-5   6-10   11-15   16-20   21-25   26-30   31-35  36-40  41-45  46-50   51-60  61-70
71-80  81-90