Question
The half-life of a radioactive substance is 10 days. The
time in which only 1/8th of the original substance remains is:Solution
When only 1/8 of the substance remains, it means 3 half-lives have passed because: (1/2)³ = 1/8 Each half-life is 10 days, so total time = 3 × 10 = 30 days. Therefore, the correct answer is 30 days.
By interchanging the given two numbers (not digits), which of the following equations will be correct?
24 and 9
I. 113 + 24 – 20 × 9 ÷...
Study the given pattern carefully and select the number that can replace the question mark (?) in it.
4 7 6
15 ? 21
44 68 60
Select the correct combination of mathematical signs that can sequentially replace '*' sign and balance the equation given below.
432 * 6 * 9 * 1...
Select the correct combination of mathematical signs that can sequentially replace the * signs and balance the given equation.
60 * 48 * 36 * 6 * 15 * 53
If '@' means '÷', '#' means ' X ', '$' means '+' and '%' means '-' then what would be the value of the expression given below?
Expression: 25 # ...
If ‘x’ denotes ‘addition’, ÷ stands for ‘subtraction’, ‘+’ stands for ‘multiplication’, and ‘-‘ stands for ‘division’, th...
Select the correct combination of mathematical signs that can sequentially replace '*' sign and balance the equation given below.
172 * 224 * 8 *...
If 34 – 28 means 952, 544 + 8 means 68, 20 ÷ 5 means 25, 20 x 10 means 10, then 375 – 11 x 270 ÷ 550 + 11 x 35 = ?
Which two digits and signs can be interchanged so as to balance the given equation?
328 - 82 + 120 X 6 ÷ 41 = 646
Which two signs should be interchanged to make the following equation correct?
38 ÷ 26 – 2 + 5 × 4 = 45