Math Review Questions

Junior High School Mathematics Contest

Preliminary Round

March 10, 1999

Question 1 of 20 5.0 Points
A final exam in Math 160 has a mean of 73 with standard deviation 7.73. Assume that a random sample of 24 students is selected and the mean test score of the sample is computed. What percentage of sample means are less than 70?
A. 19.46%
B. 12.85%
C. 2.87%
D. 13.46%

Question 2 of 20 5.0 Points
A bank’s loan officer rates applicants for credit. The ratings are normally distributed with a mean of 200 and a standard deviation of 50. If an applicant is randomly selected, find the probability of a rating that is between 225 and 275.
A. 0.2416
B. 0.2418
C. 0.2417
D. 0.2420

Review Materials for Math Competitions

Mathematics Competitions are tough! To help you find a site for your reviews, here are some of the links:

MathChallengeg1.blogspot

Enjoy and good luck with competition!

Grade 7 Mathematics-First Periodical Exam (part 1)

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DIRECTION: Read and understand each question carefully. Do not write anything on the test questionnaire. Write your answer on the answer sheet.

Multiple Choice. Choose the correct answer. Write the letter of the correct answer on the answer sheet.

1. It is a well-defined group of objects that share common characteristics.

a. Set

b. Group

c. Elements

d. Member

ANSHS Grade 7 Fourth Grading Exam

Here is the questionnaire administered for the the grade 7 of Alabel National Science High School for Fourh Grading period.

Work Problem No. 2

Greg can milk all of the carabaos in 120 minutes and Harold can do it in 60 minutes. If Greg milks for 20 minutes before Harold joins him, how long would it take them to finish?

Solution:

Let x be the length of time Greg and Harold can finish milking the carabaos.

Rate (job per minute) Time Work
Greg 1/120 x + 20 ( x + 20 ) / 120
Harold 1/60 x x/60

Equation: ( x + 20 ) / 120 + x/60 = 1

To solve, multiply both sides of the equation by the LCD, i.e.

120 ( ( x + 20 ) / 120 + x/60 ) = ( 1 ) 120
x + 20 + 2x = 120
3x + 20 = 120
3x = 120 - 20
3x = 100
x = 100/3
x = 33 1/3 minutes or 13 minutes and 20 seconds.

Therefore, Greg and Harold can milk all the carabaos in 13 minutes and 20 seconds.

Problem is taken from e-math kto12 edition Grade 7

Work Problem No. 1

Dan can do the job in 30 hours, Ellen can do it in 40 hours, and Francis can do it in 60 hours. how long would it take them if they work together?

Solution:

Let x be the number of hour Dan, Ellen, and Francis take if they work together.

Name Rate (job per hour) Time Work
Dan 1/30 x x/30
Ellen 1/40 x x/40
Francis 1/60 x x/60

Equation: x/30 + x/40 + x/60 = 1

To solve, multiply both sides of the equation by the LCD, i.e.

120 ( x/30 + x/40 + x/60 ) = ( 1 ) 120
4x + 3x + 2x = 120
9x = 120
x = 120/9
x = 13 1/3 hours or 13 hours and 20 minutes.

Therefore, Dan, Ellen, and Francis can finish the job in 13 hours and 20 minutes if they work together.

Problem is taken from e-math kto12 grade 7