Tag: writing mathematical statements

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Multiple choice maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

If the sum and the product of the digits of two digit number is the same, then the number is_____________

  1. $11$
  2. $23$
  3. $10$
  4. $22$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Let the two-digit number be 10a + b. The sum of the digits is a + b, and the product of the digits is a * b. We are given a + b = a * b. Testing the options, for 22, the sum is 2 + 2 = 4 and the product is 2 * 2 = 4, which matches the condition.

Multiple choice maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

20 years ago when my parents got married their average age was 23 years, now the average age of my family consisting of my self and my parents is 34 years, then my present age is?

  1. 14 years

  2. 16 years

  3. 18 years

  4. 36 years
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

20 years ago, the average age of the parents was 23, so their total age then was 46. Today, 20 years later, the sum of their present ages is 46 + 2 * 20 = 86 years. The current average age of the family of three (parents + child) is 34, meaning the total family age is 3 * 34 = 102 years. Subtracting the parents' total age from the family total gives the child's present age as 102 - 86 = 16 years.

Multiple choice maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

If  $12$  years hence of Ravi will he  $9$  times his age  $12$  years ago, find the present age of Ravi

  1. $12 years$
  2. $15 years$
  3. $18 years$
  4. $20 years$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Let Ravi's present age be R. 12 years hence, his age will be R + 12, and 12 years ago, his age was R - 12. According to the problem, R + 12 = 9(R - 12). Expanding this gives R + 12 = 9R - 108, which simplifies to 8R = 120, resulting in R = 15 years.

Multiple choice maths calculations and mental strategies 1 equations from statements forming equations from statements writing mathematical statements

$A$  is  $3$ times as old as  $B$  and  $C$  together. If after  $10$  years  $A's$  age would be equal sum of the ages of  $B$  and  $C .$  find the present age of  $A$

  1. $15$ years
  2. $20$ years
  3. $21$ years
  4. $25$ years
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Let A = 3(B + C). After 10 years, (A + 10) = (B + 10) + (C + 10). A + 10 = B + C + 20, so A = B + C + 10. Substituting B + C = A/3, we get A = A/3 + 10. 2A/3 = 10, so A = 15.