Six years ago Anita was P times as old as Ben was. If Anita is now 17 years old, how old is Ben now in terms of P ?
-
Solution
Let Ben's age now be B
Anita's age now is A.
(A - 6) = P(B - 6)
But A is 17 and therefore 11 = P(B - 6)
11/P = B-6
(11/P) + 6 = B
12 litres of water are poured into an aquarium of dimensions 50cm length, 30cm breadth, and 40cm height. How high (in cm) will the water rise?
(1 litre = 1000cm³)
-
Solution
Total volume of water = 12 liters = 12 x 1000 cm3
The base of the aquarium is 50 x 30 = 1500cm3
Base of tank x height of water = volume of water
1500 x height = 12000; height = 12000 / 1500 = 8
In the following correctly worked addition sum, A,B,C and D represent different digits, and all the digits in the sum are different. What is the sum of A,B,C and D?
-
Solution
First you must realize that the sum of two 2-digit numbers cannot be more that 198 (99 + 99). Therefore in the given problem D must be 1.
Now use trial and error to satisfy the sum 5A + BC = 143
A + C must give 3 in the units place, but neither can be 1 since all the digits have to be different. Therefore A + C = 13.
With one to carry over into the tens column, 1 + 5 + B = 14, and B = 8.
A + C + B + D = 13 + 8 + 1 = 22
For how many integer values of n will the value of the expression 4n + 7 be an integer greater than 1 and less than 200?
-
Solution
1 < 4n + 7 < 200
n can be 0, or -1
n cannot be -2 or any other negative integer or the expression 4n + 7 will be less than1.
The largest value for n will be an integer < (200 - 7) /4
193/4 = 48.25, hence 48
The number of integers between -1 and 48 inclusive is 50
♠n denotes the number obtained when n is rounded to the nearest tenth. For example ♠4.31 = 4.3
♠0.089 – ♠1.135 =
-
Solution
0.089 to the nearest tenth = 0.1
1.135 to the nearest tenth = 1.1
0.1 - 1.1 = -1
-20 , -16 , -12 , -8 …
In the sequence above, each term after the first is 4 greater than the preceding term. Which of the following could not be a term in the sequence?
Indicate ALL such numbers.
-
Solution
Correct Answer: E,G
Explanation:
All terms in the sequence will be multiples of 4.
762 and 902 are not multiples of 4
(65 – 64) / 5
-
Solution
65 = 64x 6
(64 x 6) - 64 = 64(6 - 1) = 64 x 5
Now, dividing by 5 will give us 64
If pqr = 1 , rst = 0 , and spr = 0, which of the following cannot be zero?
Indicate ALL such answers.
-
Solution
Correct Answer: A,B,C
Explanation:
If pqr = 1, none of these variables can be zero. Since spr = 0 , and since p and r are not zero, s must be zero. Now rst = 0, and so either s or t must be zero. Even though we have established that s is zero, there is still the possibility that t could be zero as well.
√5 percent of 5√5 =
-
Solution
We can write the statement mathematically, using x to mean of and /100 for percent. So ( √5/100) x 5√5 = 5 x 5 /100 = 0.25
The distance from town A to town B is five miles. C is six miles from B. Which of the following could be the distance from A to C?
Indicate ALL such distances.
-
Solution
Correct Answer: A,B,C
Explanation:
Do not assume that AB and C are on a straight line. Make a diagram with A and B marked 5 miles apart. Draw a circle centered on B, with radius 6. C could be anywhere on this circle. The minimum distance will be 1, and maximum 11, but anywhere in between is possible.