Math Kangaroo 2021 Problem 17 | Kadett

Try this beautiful Problem based on simple Arithmetic appeared in Math Kangaroo (Kadett) 2021 Problem 17.

Math Kangaroo 2021 Problem 17 | Kadett

There are 20 questions in a quiz. Each correct answer scores 7 points, each wrong answer scores $-4$ points, and each question left blank scores 0 points. Eric took the quiz and scored 100 points. How many questions did he leave blank?

Key Concepts

Arithmetic

Divisibility

Logic Question

Suggested Book | Source | Answer

Algebra by Gelfand

Math Kangaroo (Kadett), 2021

$1$

Try with Hints

Here given that,

Total number of questions $=20$
Score of correct answer $=7$ points
Score of wrong answer $=-4$
Eric scored $=100$ points

So that mean, the score for all of the correct answers is greater than $100$.

Now we know $7\times 16 = 112$.

Now we have to count how many wrong answers are there if the score is $100$.

Remaining question $=20-(16+3)$
So, $1$ is the correct answer.

Math Kangaroo 2021 Problem 21 | Ecolier

Try this beautiful Problem based on simple Divisibility Rules appeared in Math Kangaroo (Ecolier) 2021 Problem 21.

Math Kangaroo 2021 Problem No 21 | Ecolier

A box has fewer than 50 cookies in. The cookies can be divided evenly between 2,3 , or 4 children. However, they cannot be divided evenly between 7 children because 6 more cookies would be needed. How many cookies are there in the box?

Key Concepts

Arithmetic

Divisibility

Algebra

Suggested Book | Source | Answer

Algebra by Gelfand

Math Kangaroo (Ecolier), 2021

$36$

Try with Hints

Here

The box contain less than 50 cookies.

Cookies are distributed among 2, 3 or 4 children.

So, all of the options are correct.

Now apply the second condition in the question.

They cannot be divided evenly between 7 children because 6 more cookies would be needed.

Apply the condition and check which option is satisfying the condition.

So, $36$ is the correct answer.

Math Kangaroo 2021 Problem 17 | Kadett